diff --git a/doc/Pacemaker_Explained/en-US/Ap-LSB.txt b/doc/Pacemaker_Explained/en-US/Ap-LSB.txt index 3a8aaffc11..42a210979d 100644 --- a/doc/Pacemaker_Explained/en-US/Ap-LSB.txt +++ b/doc/Pacemaker_Explained/en-US/Ap-LSB.txt @@ -1,71 +1,77 @@ [appendix] == init-Script LSB Compliance == anchor:ap-lsb[LSB Compliance] The relevant part of http://refspecs.freestandards.org/LSB_3.1.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html[LSB spec] includes a description of all the return codes listed here. Assuming +some_service+ is configured correctly and currently not active, the following sequence will help you determine if it is LSB compatible: . Start (stopped): + -`/etc/init.d/some_service start ; echo "result: $?"` +[source,C] +# /etc/init.d/some_service start ; echo "result: $?" + .. Did the service start? .. Did the command print result: 0 (in addition to the regular output)? + . Status (running): + -`/etc/init.d/some_service status ; echo "result: $?"` +[source,C] +# /etc/init.d/some_service status ; echo "result: $?" + .. Did the script accept the command? .. Did the script indicate the service was running? .. Did the command print result: 0 (in addition to the regular output)? + . Start (running): + -`/etc/init.d/some_service start ; echo "result: $?"` +[source,C] +# /etc/init.d/some_service start ; echo "result: $?" + .. Is the service still running? .. Did the command print result: 0 (in addition to the regular output)? + . Stop (running): + -`/etc/init.d/some_service stop ; echo "result: $?"` +[source,C] +# /etc/init.d/some_service stop ; echo "result: $?" + .. Was the service stopped? .. Did the command print result: 0 (in addition to the regular output)? + . Status (stopped): + -`/etc/init.d/some_service status ; echo "result: $?"` +[source,C] +# /etc/init.d/some_service status ; echo "result: $?" + .. Did the script accept the command? .. Did the script indicate the service was not running? .. Did the command print result: 3 (in addition to the regular output)? + . Stop (stopped): + -`/etc/init.d/some_service stop ; echo "result: $?"` +[source,C] +# /etc/init.d/some_service stop ; echo "result: $?" + .. Is the service still stopped? .. Did the command print result: 0 (in addition to the regular output)? + . Status (failed): + This step is not readily testable and relies on manual inspection of the script. + The script can use one of the error codes (other than 3) listed in the LSB spec to indicate that it is active but failed. This tells the cluster that before moving the resource to another node, it needs to stop it on the existing one first. If the answer to any of the above questions is no, then the script is not LSB compliant. Your options are then to either fix the script or write an OCF agent based on the existing script. diff --git a/doc/Pacemaker_Explained/en-US/Ap-Samples.txt b/doc/Pacemaker_Explained/en-US/Ap-Samples.txt index bf17efe126..1021b4508b 100644 --- a/doc/Pacemaker_Explained/en-US/Ap-Samples.txt +++ b/doc/Pacemaker_Explained/en-US/Ap-Samples.txt @@ -1,141 +1,147 @@ [appendix] == Sample Configurations == === Empty === indexterm:[Configuration,Empty] .An Empty Configuration +======= [source,XML] ------- ------- +======= === Simple === indexterm:[Configuration,Simple] .Simple Configuration - 2 nodes, some cluster options and a resource +======= [source,XML] ------- ------- +======= In this example, we have one resource (an IP address) that we check every five minutes and will run on host +c001n01+ until either the resource fails 10 times or the host shuts down. === Advanced Configuration === indexterm:[Configuration,Advanced] .Advanced configuration - groups and clones with stonith +======= [source,XML] ------- ------- +======= diff --git a/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.txt b/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.txt index 8605f5f805..4ffe0c7c85 100644 --- a/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.txt +++ b/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.txt @@ -1,140 +1,138 @@ [appendix] == Upgrading the Configuration from 0.6 == === Preparation === indexterm:[Upgrading the Configuration] indexterm:[Configuration,Upgrading] indexterm:[Download,DTD] indexterm:[DTD,Download] Download the latest http://hg.clusterlabs.org/pacemaker/stable-1.0/file-raw/tip/xml/crm.dtd[DTD] and ensure your configuration validates. === Perform the upgrade === ==== Upgrade the software ==== Refer to the appendix: xref:ap-upgrade[] ==== Upgrade the Configuration ==== As XML is not the friendliest of languages, it is common for cluster administrators to have scripted some of their activities. In such cases, it is likely that those scripts will not work with the new 1.0 syntax. In order to support such environments, it is actually possible to continue using the old 0.6 syntax. The downside is, however, that not all the new features will be available and there is a performance impact since the cluster must do a non-persistent configuration upgrade before each transition. So while using the old syntax is possible, it is not advisable to continue using it indefinitely. Even if you wish to continue using the old syntax, it is advisable to follow the upgrade procedure to ensure that the cluster is able to use your existing configuration (since it will perform much the same task internally). . Create a shadow copy to work with indexterm:[shadow copy,example for upgrading] + -[source,Bash] +[source,C] ----- -crm_shadow --create upgrade06 +# crm_shadow --create upgrade06 ----- . Verify the configuration is valid indexterm:[Configuration,Verify]indexterm:[Verify,Configuration] + -[source,Bash] +[source,C] ----- -crm_verify --live-check +# crm_verify --live-check ----- . Fix any errors or warnings . Perform the upgrade: + -[source,Bash] +[source,C] ----- -cibadmin --upgrade +# cibadmin --upgrade ----- . If this step fails, there are three main possibilities: .. The configuration was not valid to start with - go back to step 2 .. The transformation failed - report a bug or mailto:pacemaker@oss.clusterlabs.org?subject=Transformation%20failed%20during%20upgrade[email the project] .. The transformation was successful but produced an invalid result footnote:[ The most common reason is ID values being repeated or invalid. Pacemaker 1.0 is much stricter regarding this type of validation. ] + If the result of the transformation is invalid, you may see a number of errors from the validation library. If these are not helpful, visit http://clusterlabs.org/wiki/Validation_FAQ and/or try the procedure described below under xref:s-upgrade-config-manual[] + . Check the changes + -[source,Bash] +[source,C] ----- -crm_shadow --diff +# crm_shadow --diff ----- + If at this point there is anything about the upgrade that you wish to fine-tune (for example, to change some of the automatic IDs) now is the time to do so. Since the shadow configuration is not in use by the cluster, it is safe to edit the file manually: + -[source,Bash] +[source,C] ----- -crm_shadow --edit +# crm_shadow --edit ----- + This will open the configuration in your favorite editor (whichever is specified by the standard +$EDITOR+ environment variable) + . Preview how the cluster will react + Test what the cluster will do when you upload the new configuration + -[source,Bash] +[source,C] ------ -crm_simulate --live-check --save-dotfile upgrade06.dot -S -graphviz upgrade06.dot +# crm_simulate --live-check --save-dotfile upgrade06.dot -S +# graphviz upgrade06.dot ------ + Verify that either no resource actions will occur or that you are happy with any that are scheduled. If the output contains actions you do not expect (possibly due to changes to the score calculations), you may need to make further manual changes. See xref:s-config-testing-changes[] for further details on how to interpret the output of `crm_simulate` + . Upload the changes + -[source,Bash] +[source,C] ----- -crm_shadow --commit upgrade06 --force +# crm_shadow --commit upgrade06 --force ----- If this step fails, something really strange has occurred. You should report a bug. ==== Manually Upgrading the Configuration ==== anchor:s-upgrade-config-manual[Manually Upgrading the Configuration] indexterm:[Configuration,Upgrade manually] It is also possible to perform the configuration upgrade steps manually. To do this Locate the 'upgrade06.xsl' conversion script or download the latest version from https://github.com/ClusterLabs/pacemaker/tree/master/xml/upgrade06.xsl[Git] . Convert the XML blob: indexterm:[XML,Convert] + -[source,Bash] +[source,C] ----- -xsltproc /path/to/upgrade06.xsl config06.xml > config10.xml +# xsltproc /path/to/upgrade06.xsl config06.xml > config10.xml ----- + . Locate the 'pacemaker.rng' script. . Check the XML validity: indexterm:[Validate,XML]indexterm:[xmllint,Validate XML] + -[source,Bash] ------ -xmllint --relaxng /path/to/pacemaker.rng config10.xml ------ +[source,C] +# xmllint --relaxng /path/to/pacemaker.rng config10.xml The advantage of this method is that it can be performed without the cluster running and any validation errors should be more informative (despite being generated by the same library!) since they include line numbers. diff --git a/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.xml b/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.xml index b08a468e5e..b21acbdb8d 100644 --- a/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.xml +++ b/doc/Pacemaker_Explained/en-US/Ap-Upgrade-Config.xml @@ -1,210 +1,212 @@ + + Upgrading the Configuration from 0.6
Preparation Upgrading the Configuration ConfigurationUpgrading Upgrading DownloadDTD DTD DTDDownload Download Download the latest DTD and ensure your configuration validates.
Perform the upgrade
Upgrade the software Refer to the appendix:
Upgrade the Configuration As XML is not the friendliest of languages, it is common for cluster administrators to have scripted some of their activities. In such cases, it is likely that those scripts will not work with the new 1.0 syntax. In order to support such environments, it is actually possible to continue using the old 0.6 syntax. The downside is, however, that not all the new features will be available and there is a performance impact since the cluster must do a non-persistent configuration upgrade before each transition. So while using the old syntax is possible, it is not advisable to continue using it indefinitely. Even if you wish to continue using the old syntax, it is advisable to follow the upgrade procedure to ensure that the cluster is able to use your existing configuration (since it will perform much the same task internally). Create a shadow copy to work with shadow copyexample for upgrading example for upgrading -crm_shadow --create upgrade06 +# crm_shadow --create upgrade06 Verify the configuration is valid ConfigurationVerify Verify VerifyConfiguration Configuration -crm_verify --live-check +# crm_verify --live-check Fix any errors or warnings Perform the upgrade: -cibadmin --upgrade +# cibadmin --upgrade If this step fails, there are three main possibilities: The configuration was not valid to start with - go back to step 2 The transformation failed - report a bug or email the project The transformation was successful but produced an invalid result The most common reason is ID values being repeated or invalid. Pacemaker 1.0 is much stricter regarding this type of validation. If the result of the transformation is invalid, you may see a number of errors from the validation library. If these are not helpful, visit http://clusterlabs.org/wiki/Validation_FAQ and/or try the procedure described below under Check the changes -crm_shadow --diff +# crm_shadow --diff If at this point there is anything about the upgrade that you wish to fine-tune (for example, to change some of the automatic IDs) now is the time to do so. Since the shadow configuration is not in use by the cluster, it is safe to edit the file manually: -crm_shadow --edit +# crm_shadow --edit This will open the configuration in your favorite editor (whichever is specified by the standard $EDITOR environment variable) Preview how the cluster will react Test what the cluster will do when you upload the new configuration -crm_simulate --live-check --save-dotfile upgrade06.dot -S -graphviz upgrade06.dot +# crm_simulate --live-check --save-dotfile upgrade06.dot -S +# graphviz upgrade06.dot Verify that either no resource actions will occur or that you are happy with any that are scheduled. If the output contains actions you do not expect (possibly due to changes to the score calculations), you may need to make further manual changes. See for further details on how to interpret the output of crm_simulate Upload the changes -crm_shadow --commit upgrade06 --force +# crm_shadow --commit upgrade06 --force If this step fails, something really strange has occurred. You should report a bug.
Manually Upgrading the Configuration ConfigurationUpgrade manually Upgrade manually It is also possible to perform the configuration upgrade steps manually. To do this Locate the upgrade06.xsl conversion script or download the latest version from Git Convert the XML blob: XMLConvert Convert -xsltproc /path/to/upgrade06.xsl config06.xml > config10.xml +# xsltproc /path/to/upgrade06.xsl config06.xml > config10.xml Locate the pacemaker.rng script. Check the XML validity: ValidateXML XML xmllintValidate XML Validate XML -xmllint --relaxng /path/to/pacemaker.rng config10.xml +# xmllint --relaxng /path/to/pacemaker.rng config10.xml The advantage of this method is that it can be performed without the cluster running and any validation errors should be more informative (despite being generated by the same library!) since they include line numbers.
diff --git a/doc/Pacemaker_Explained/en-US/Ap-Upgrade.txt b/doc/Pacemaker_Explained/en-US/Ap-Upgrade.txt index 1130607087..33e19b01d6 100644 --- a/doc/Pacemaker_Explained/en-US/Ap-Upgrade.txt +++ b/doc/Pacemaker_Explained/en-US/Ap-Upgrade.txt @@ -1,216 +1,216 @@ [appendix] == Upgrading Cluster Software anchor:ap-upgrade[Upgrading Cluster Software] === Version Compatibility === When releasing newer versions we take care to make sure we are backwards compatible with older versions. While you will always be able to upgrade from version x to x+1, in order to continue to produce high quality software it may occasionally be necessary to drop compatibility with older versions. There will always be an upgrade path from any series-2 release to any other series-2 release. There are three approaches to upgrading your cluster software: * Complete Cluster Shutdown * Rolling (node by node) * Disconnect and Reattach Each method has advantages and disadvantages, some of which are listed in the table below, and you should chose the one most appropriate to your needs. .Summary of Upgrade Methodologies [width="95%",cols="6*",options="header",align="center"] |========================================================= |Type |Available between all software versions |Service Outage During Upgrade |Service Recovery During Upgrade |Exercises Failover Logic/Configuration |Allows change of cluster stack type indexterm:[Cluster Stack,switching between] indexterm:[Changing Cluster Stack] footnote:[ For example, switching from Heartbeat to Corosync. Consult the Heartbeat or Corosync documentation to see if upgrading them to a newer version is also supported. ] |Shutdown indexterm:[Upgrade,Shutdown] indexterm:[Shutdown Upgrade] |yes |always |N/A |no |yes |Rolling indexterm:[Upgrade,Rolling] indexterm:[Rolling Upgrade] |no |always |yes |yes |no |Reattach indexterm:[Upgrade,Reattach] indexterm:[Reattach Upgrade] |yes |only due to failure |no |no |yes |========================================================= === Complete Cluster Shutdown === In this scenario one shuts down all cluster nodes and resources and upgrades all the nodes before restarting the cluster. ==== Procedure ==== . On each node: .. Shutdown the cluster stack (Heartbeat or Corosync) .. Upgrade the Pacemaker software. This may also include upgrading the cluster stack and/or the underlying operating system. .. Check the configuration manually or with the `crm_verify` tool if available. . On each node: .. Start the cluster stack. This can be either Corosync or Heartbeat and does not need to be the same as the previous cluster stack. === Rolling (node by node) === In this scenario each node is removed from the cluster, upgraded and then brought back online until all nodes are running the newest version. [IMPORTANT] =========== This method is currently broken between Pacemaker 0.6.x and 1.0.x. Measures have been put into place to ensure rolling upgrades always work for versions after 1.0.0. Please try one of the other upgrade strategies. Detach/Reattach is a particularly good option for most people. =========== ==== Procedure ==== On each node: . Shutdown the cluster stack (Heartbeat or Corosync) . Upgrade the Pacemaker software. This may also include upgrading the cluster stack and/or the underlying operating system. .. On the first node, check the configuration manually or with the `crm_verify` tool if available. .. Start the cluster stack. + This must be the same type of cluster stack (Corosync or Heartbeat) that the rest of the cluster is using. Upgrading Corosync/Heartbeat may also be possible, please consult the documentation for those projects to see if the two versions will be compatible. + .. Repeat for each node in the cluster. ==== Version Compatibility ==== .Version Compatibility Table [width="95%",cols="2*",options="header",align="center"] |========================================================= |Version being Installed |Oldest Compatible Version |Pacemaker 1.0.x |Pacemaker 1.0.0 |Pacemaker 0.7.x |Pacemaker 0.6 or Heartbeat 2.1.3 |Pacemaker 0.6.x |Heartbeat 2.0.8 |Heartbeat 2.1.3 (or less) |Heartbeat 2.0.4 |Heartbeat 2.0.4 (or less) |Heartbeat 2.0.0 |Heartbeat 2.0.0 |None. Use an alternate upgrade strategy. |========================================================= ==== Crossing Compatibility Boundaries ==== Rolling upgrades that cross compatibility boundaries must be preformed in multiple steps. For example, to perform a rolling update from Heartbeat 2.0.1 to Pacemaker 0.6.6 one must: . Perform a rolling upgrade from Heartbeat 2.0.1 to Heartbeat 2.0.4 . Perform a rolling upgrade from Heartbeat 2.0.4 to Heartbeat 2.1.3 . Perform a rolling upgrade from Heartbeat 2.1.3 to Pacemaker 0.6.6 === Disconnect and Reattach === A variant of a complete cluster shutdown, but the resources are left active and get re-detected when the cluster is restarted. ==== Procedure ==== . Tell the cluster to stop managing services. + This is required to allow the services to remain active after the cluster shuts down. + -[source,Bash] -crm_attribute -t crm_config -n is-managed-default -v false +[source,C] +# crm_attribute -t crm_config -n is-managed-default -v false + . For any resource that has a value for +is-managed+, make sure it is set to +false+ (so that the cluster will not stop it) + -[source,Bash] -crm_resource -t primitive -r $rsc_id -p is-managed -v false +[source,C] +# crm_resource -t primitive -r $rsc_id -p is-managed -v false + . On each node: .. Shutdown the cluster stack (Heartbeat or Corosync) .. Upgrade the cluster stack program - This may also include upgrading the underlying operating system. . Check the configuration manually or with the `crm_verify` tool if available. . On each node: .. Start the cluster stack. + This can be either Corosync or Heartbeat and does not need to be the same as the previous cluster stack. + . Verify that the cluster re-detected all resources correctly. . Allow the cluster to resume managing resources again: + -[source,Bash] -crm_attribute -t crm_config -n is-managed-default -v true +[source,C] +# crm_attribute -t crm_config -n is-managed-default -v true + . For any resource that has a value for +is-managed+ reset it to +true+ (so the cluster can recover the service if it fails) if desired: + -[source,Bash] -crm_resource -t primitive -r $rsc_id -p is-managed -v true +[source,C] +# crm_resource -t primitive -r $rsc_id -p is-managed -v true ==== Notes ==== [IMPORTANT] =========== Always check your existing configuration is still compatible with the version you are installing before starting the cluster. =========== [NOTE] The oldest version of the CRM to support this upgrade type was in Heartbeat 2.0.4 diff --git a/doc/Pacemaker_Explained/en-US/Ch-Advanced-Options.txt b/doc/Pacemaker_Explained/en-US/Ch-Advanced-Options.txt index 5881cf8a30..57a541c1f1 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Advanced-Options.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Advanced-Options.txt @@ -1,657 +1,679 @@ = Advanced Configuration = == Connecting from a Remote Machine == indexterm:[Remote,connect] indexterm:[Remote,administration] anchor:s-remote-connection[Connecting from a Remote Machine] Provided Pacemaker is installed on a machine, it is possible to connect to the cluster even if the machine itself is not in the same cluster. To do this, one simply sets up a number of environment variables and runs the same commands as when working on a cluster node. .Environment Variables Used to Connect to Remote Instances of the CIB -[width="95%",cols="1m,4<",options="header",align="center"] +[width="95%",cols="1m,2<",options="header",align="center"] |========================================================= |Environment Variable |Description indexterm:[Environment Variable,Remote Administration] |CIB_user |The user to connect as. Needs to be part of the +hacluster+ group on the target host. Defaults to _$USER_. indexterm:[CIB_*, Env. Var. for Remote Conn.,user] indexterm:[Environment Variable,CIB_,user] |CIB_passwd |The user's password. Read from the command line if unset. indexterm:[CIB_*, Env. Var. for Remote Conn.,passwd] indexterm:[Environment Variable,CIB_,passwd] |CIB_server |The host to contact. Defaults to _localhost_. indexterm:[CIB_*, Env. Var. for Remote Conn.,server] indexterm:[Environment Variable,CIB_,server] |CIB_port |The port on which to contact the server; required. indexterm:[CIB_*, Env. Var. for Remote Conn.,port] indexterm:[Environment Variable,CIB_,port] |CIB_encrypted |Encrypt network traffic; defaults to _true_. indexterm:[CIB_*, Env. Var. for Remote Conn.,encrypted] indexterm:[Environment Variable,CIB_,encrypted] |========================================================= So, if +c001n01+ is an active cluster node and is listening on +1234+ for connections, and +someguy+ is a member of the +hacluster+ group, then the following would prompt for +someguy+'s password and return the cluster's current configuration: -[source,Bash] -export CIB_port=1234; export CIB_server=c001n01; export CIB_user=someguy; -cibadmin -Q +[source,C] +# export CIB_port=1234; export CIB_server=c001n01; export CIB_user=someguy; +# cibadmin -Q For security reasons, the cluster does not listen for remote connections by default. If you wish to allow remote access, you need to set the +remote-tls-port+ (encrypted) or +remote-clear-port+ (unencrypted) top-level options (ie., those kept in the cib tag, like +num_updates+ and +epoch+). indexterm:[Remote,connect, CIB options] .Extra top-level CIB options for remote access [width="95%",cols="1m,2<",options="header",align="center"] |========================================================= |Field |Description |remote-tls-port |Listen for encrypted remote connections on this port. Default: _none_ indexterm:[remote-tls-port] |remote-clear-port |Listen for plaintext remote connections on this port. Default: _none_ indexterm:[remote-clear-port] |========================================================= == Specifying When Recurring Actions are Performed == anchor:s-recurring-start[Specifying When Recurring Actions are Performed] By default, recurring actions are scheduled relative to when the resource started. So if your resource was last started at 14:32 and you have a backup set to be performed every 24 hours, then the backup will always run at in the middle of the business day - hardly desirable. To specify a date/time that the operation should be relative to, set the operation's +interval-origin+. The cluster uses this point to calculate the correct +start-delay+ such that the operation will occur at _origin + (interval * N)_. So, if the operation's interval is 24h, it's interval-origin is set to +02:00+ and it is currently +14:32+, then the cluster would initiate the operation with a start delay of 11 hours and 28 minutes. If the resource is moved to another node before 2am, then the operation is of course cancelled. The value specified for interval and +interval-origin+ can be any date/time conforming to the http://en.wikipedia.org/wiki/ISO_8601[ISO8601 standard]. By way of example, to specify an operation that would run on the first Monday of 2009 and every Monday after that you would add: .Specifying a Base for Recurring Action Intervals +===== [source,XML] +===== == Moving Resources == indexterm:[Moving Resources] indexterm:[Resource,Moving] === Manual Intervention === There are primarily two occasions when you would want to move a resource from it's current location: when the whole node is under maintenance, and when a single resource needs to be moved. Since everything eventually comes down to a score, you could create constraints for every resource to prevent them from running on one node. While the configuration can seem convoluted at times, not even we would require this of administrators. Instead one can set a special node attribute which tells the cluster "don't let anything run here". There is even a helpful tool to help query and set it, called `crm_standby`. To check the standby status of the current machine, simply run: -[source,Bash] -crm_standby --get-value +[source,C] +# crm_standby --get-value A value of +true+ indicates that the node is _NOT_ able to host any resources, while a value of +false+ says that it _CAN_. You can also check the status of other nodes in the cluster by specifying the `--node-uname` option: -[source,Bash] -crm_standby --get-value --node-uname sles-2 +[source,C] +# crm_standby --get-value --node-uname sles-2 To change the current node's standby status, use `--attr-value` instead of `--get-value`. -[source,Bash] -crm_standby --attr-value +[source,C] +# crm_standby --attr-value Again, you can change another host's value by supplying a host name with `--node-uname`. When only one resource is required to move, we do this by creating location constraints. However, once again we provide a user friendly shortcut as part of the `crm_resource` command, which creates and modifies the extra constraints for you. If +Email+ was running on +sles-1+ and you wanted it moved to a specific location, the command would look something like: -[source,Bash] -crm_resource -M -r Email -H sles-2 +[source,C] +# crm_resource -M -r Email -H sles-2 Behind the scenes, the tool will create the following location constraint: [source,XML] It is important to note that subsequent invocations of `crm_resource -M` are not cumulative. So, if you ran these commands -[source,Bash] -crm_resource -M -r Email -H sles-2 -crm_resource -M -r Email -H sles-3 +[source,C] +# crm_resource -M -r Email -H sles-2 +# crm_resource -M -r Email -H sles-3 then it is as if you had never performed the first command. To allow the resource to move back again, use: -[source,Bash] -crm_resource -U -r Email +[source,C] +# crm_resource -U -r Email Note the use of the word _allow_. The resource can move back to its original location but, depending on +resource-stickiness+, it might stay where it is. To be absolutely certain that it moves back to +sles-1+, move it there before issuing the call to `crm_resource -U`: -[source,Bash] -crm_resource -M -r Email -H sles-1 -crm_resource -U -r Email +[source,C] +# crm_resource -M -r Email -H sles-1 +# crm_resource -U -r Email Alternatively, if you only care that the resource should be moved from its current location, try -[source,Bash] -crm_resource -M -r Email` +[source,C] +# crm_resource -M -r Email` Which will instead create a negative constraint, like [source,XML] This will achieve the desired effect, but will also have long-term consequences. As the tool will warn you, the creation of a +-INFINITY+ constraint will prevent the resource from running on that node until `crm_resource -U` is used. This includes the situation where every other cluster node is no longer available! In some cases, such as when +resource-stickiness+ is set to +INFINITY+, it is possible that you will end up with the problem described in xref:node-score-equal[]. The tool can detect some of these cases and deals with them by also creating both a positive and negative constraint. Eg. +Email+ prefers +sles-1+ with a score of +-INFINITY+ +Email+ prefers +sles-2+ with a score of +INFINITY+ which has the same long-term consequences as discussed earlier. === Moving Resources Due to Failure === anchor:s-failure-migration[Moving Resources Due to Failure] New in 1.0 is the concept of a migration threshold. footnote:[ The naming of this option was perhaps unfortunate as it is easily confused with true migration, the process of moving a resource from one node to another without stopping it. Xen virtual guests are the most common example of resources that can be migrated in this manner. ] Simply define +migration-threshold=N+ for a resource and it will migrate to a new node after N failures. There is no threshold defined by default. To determine the resource's current failure status and limits, use `crm_mon --failcounts`. By default, once the threshold has been reached, this node will no longer be allowed to run the failed resource until the administrator manually resets the resource's failcount using `crm_failcount` (after hopefully first fixing the failure's cause). However it is possible to expire them by setting the resource's +failure-timeout+ option. So a setting of +migration-threshold=2+ and +failure-timeout=60s+ would cause the resource to move to a new node after 2 failures, and allow it to move back (depending on the stickiness and constraint scores) after one minute. There are two exceptions to the migration threshold concept; they occur when a resource either fails to start or fails to stop. Start failures cause the failcount to be set to +INFINITY+ and thus always cause the resource to move immediately. Stop failures are slightly different and crucial. If a resource fails to stop and STONITH is enabled, then the cluster will fence the node in order to be able to start the resource elsewhere. If STONITH is not enabled, then the cluster has no way to continue and will not try to start the resource elsewhere, but will try to stop it again after the failure timeout. [IMPORTANT] Please read xref:s-rules-recheck[] before enabling this option. === Moving Resources Due to Connectivity Changes === Setting up the cluster to move resources when external connectivity is lost is a two-step process. ==== Tell Pacemaker to monitor connectivity ==== To do this, you need to add a +ping+ resource to the cluster. The +ping+ resource uses the system utility of the same name to a test if list of machines (specified by DNS hostname or IPv4/IPv6 address) are reachable and uses the results to maintain a node attribute normally called +pingd+. footnote:[ The attribute name is customizable; that allows multiple ping groups to be defined. ] [NOTE] Older versions of Heartbeat required users to add ping nodes to _ha.cf_ - this is no longer required. [IMPORTANT] =========== Older versions of Pacemaker used a custom binary called 'pingd' for this functionality; this is now deprecated in favor of 'ping'. If your version of Pacemaker does not contain the ping agent, you can download the latest version from https://github.com/ClusterLabs/pacemaker/tree/master/extra/resources/ping =========== Normally the resource will run on all cluster nodes, which means that you'll need to create a clone. A template for this can be found below along with a description of the most interesting parameters. .Common Options for a 'ping' Resource [width="95%",cols="1m,4<",options="header",align="center"] |========================================================= |Field |Description |dampen |The time to wait (dampening) for further changes to occur. Use this to prevent a resource from bouncing around the cluster when cluster nodes notice the loss of connectivity at slightly different times. indexterm:[dampen,Resource Option] indexterm:[Resource,Option,dampen] |multiplier |The number of connected ping nodes gets multiplied by this value to get a score. Useful when there are multiple ping nodes configured. indexterm:[multiplier,Resource Option] indexterm:[Resource,Option,multiplier] |host_list |The machines to contact in order to determine the current connectivity status. Allowed values include resolvable DNS host names, IPv4 and IPv6 addresses. indexterm:[host_list,Resource Option] indexterm:[Resource,Option,host_list] |========================================================= -An example ping cluster resource that checks node connectivity once every minute: +.An example ping cluster resource that checks node connectivity once every minute +===== [source,XML] ------------ ------------ +===== [IMPORTANT] =========== You're only half done. The next section deals with telling Pacemaker how to deal with the connectivity status that +ocf:pacemaker:ping+ is recording. =========== ==== Tell Pacemaker how to interpret the connectivity data ==== [NOTE] ====== Before reading the following, please make sure you have read and understood xref:ch-rules[] above. ====== There are a number of ways to use the connectivity data provided by Heartbeat. The most common setup is for people to have a single ping node, to prevent the cluster from running a resource on any unconnected node. //// TODO: is the idea that only nodes that can reach eg. the router should have active resources? //// .Don't run on unconnected nodes +===== [source,XML] ------- ------- +===== A more complex setup is to have a number of ping nodes configured. You can require the cluster to only run resources on nodes that can connect to all (or a minimum subset) of them. -Run only on nodes connected to three or more ping nodes; this assumes +multiplier+ is set to 1000: +.Run only on nodes connected to three or more ping nodes; this assumes +multiplier+ is set to 1000: +===== [source,XML] ------- ------- +===== Instead you can tell the cluster only to _prefer_ nodes with the best connectivity. Just be sure to set +multiplier+ to a value higher than that of +resource-stickiness+ (and don't set either of them to +INFINITY+). .Prefer the node with the most connected ping nodes +===== [source,XML] ------- ------- +===== It is perhaps easier to think of this in terms of the simple constraints that the cluster translates it into. For example, if +sles-1+ is connected to all 5 ping nodes but +sles-2+ is only connected to 2, then it would be as if you instead had the following constraints in your configuration: .How the cluster translates the pingd constraint +===== [source,XML] ------- ------- +===== The advantage is that you don't have to manually update any constraints whenever your network connectivity changes. You can also combine the concepts above into something even more complex. The example below shows how you can prefer the node with the most connected ping nodes provided they have connectivity to at least three (again assuming that +multiplier+ is set to 1000). .A more complex example of choosing a location based on connectivity +===== [source,XML] ------- ------- +===== === Resource Migration === Some resources, such as Xen virtual guests, are able to move to another location without loss of state. We call this resource migration; this is different from the normal practice of stopping the resource on the first machine and starting it elsewhere. Not all resources are able to migrate, see the Migration Checklist below, and those that can, won't do so in all situations. Conceptually there are two requirements from which the other prerequisites follow: * the resource must be active and healthy at the old location * everything required for the resource to run must be available on both the old and new locations The cluster is able to accommodate both push and pull migration models by requiring the resource agent to support two new actions: +migrate_to+ (performed on the current location) and +migrate_from+ (performed on the destination). In push migration, the process on the current location transfers the resource to the new location where is it later activated. In this scenario, most of the work would be done in the +migrate_to+ action and, if anything, the activation would occur during +migrate_from+. Conversely for pull, the +migrate_to+ action is practically empty and +migrate_from+ does most of the work, extracting the relevant resource state from the old location and activating it. There is no wrong or right way to implement migration for your service, as long as it works. ==== Migration Checklist ==== * The resource may not be a clone. * The resource must use an OCF style agent. * The resource must not be in a failed or degraded state. * The resource must not, directly or indirectly, depend on any primitive or group resources. * The resource must support two new actions: +migrate_to+ and +migrate_from+, and advertise them in its metadata. * The resource must have the +allow-migrate+ meta-attribute set to +true+ (which is not the default). //// TODO: how can a KVM with DRBD migrate? //// If the resource depends on a clone, and at the time the resource needs to be move, the clone has instances that are stopping and instances that are starting, then the resource will be moved in the traditional manner. The Policy Engine is not yet able to model this situation correctly and so takes the safe (yet less optimal) path. == Reusing Rules, Options and Sets of Operations == anchor:s-reusing-config-elements[Reusing Rules, Options and Sets of Operations] Sometimes a number of constraints need to use the same set of rules, and resources need to set the same options and parameters. To simplify this situation, you can refer to an existing object using an +id-ref+ instead of an id. So if for one resource you have [source,XML] ------ ------ Then instead of duplicating the rule for all your other resources, you can instead specify: .Referencing rules from other constraints +===== [source,XML] ------- ------- +===== [IMPORTANT] =========== The cluster will insist that the +rule+ exists somewhere. Attempting to add a reference to a non-existing rule will cause a validation failure, as will attempting to remove a +rule+ that is referenced elsewhere. =========== The same principle applies for +meta_attributes+ and +instance_attributes+ as illustrated in the example below: .Referencing attributes, options, and operations from other resources +===== [source,XML] ------- ------- +===== == Reloading Services After a Definition Change == The cluster automatically detects changes to the definition of services it manages. However, the normal response is to stop the service (using the old definition) and start it again (with the new definition). This works well, but some services are smarter and can be told to use a new set of options without restarting. To take advantage of this capability, your resource agent must: . Accept the +reload+ operation and perform any required actions. _The steps required here depend completely on your application!_ + .The DRBD Agent's Control logic for Supporting the +reload+ Operation +===== [source,Bash] ------- case $1 in start) drbd_start ;; stop) drbd_stop ;; reload) drbd_reload ;; monitor) drbd_monitor ;; *) drbd_usage exit $OCF_ERR_UNIMPLEMENTED ;; esac exit $? ------- +===== . Advertise the +reload+ operation in the +actions+ section of its metadata - This is how the DRBD Agent advertisese Support for the +reload+ operation: + .The DRBD Agent Advertising Support for the +reload+ Operation +===== [source,XML] ------- 1.1 Master/Slave OCF Resource Agent for DRBD ... ------- +===== . Advertise one or more parameters that can take effect using +reload+. + Any parameter with the +unique+ set to 0 is eligible to be used in this way. -For example, the drbdconf parameter from the drbd agent: + .Parameter that can be changed using reload +===== [source,XML] ------- Full path to the drbd.conf file. Path to drbd.conf ------- +===== Once these requirements are satisfied, the cluster will automatically know to reload the resource (instead of restarting) when a non-unique fields changes. [NOTE] ====== The metadata is re-read when the resource is started. This may mean that the resource will be restarted the first time, even though you changed a parameter with +unique=0+ ====== [NOTE] ====== If both a unique and non-unique field are changed simultaneously, the resource will still be restarted. ====== diff --git a/doc/Pacemaker_Explained/en-US/Ch-Advanced-Resources.txt b/doc/Pacemaker_Explained/en-US/Ch-Advanced-Resources.txt index 397dfec285..9d21ca48dc 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Advanced-Resources.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Advanced-Resources.txt @@ -1,940 +1,959 @@ = Advanced Resource Types = == Groups - A Syntactic Shortcut == indexterm:[Group Resources] indexterm:[Resources,Groups] anchor:group-resources[Group Resources] One of the most common elements of a cluster is a set of resources that need to be located together, start sequentially, and stop in the reverse order. To simplify this configuration we support the concept of groups. .An example group +====== [source,XML] ------- ------- +====== Although the example above contains only two resources, there is no limit to the number of resources a group can contain. The example is also sufficient to explain the fundamental properties of a group: * Resources are started in the order they appear in (+Public-IP+ first, then +Email+) * Resources are stopped in the reverse order to which they appear in (+Email+ first, then +Public-IP+) If a resource in the group can't run anywhere, then nothing after that is allowed to run, too. * If +Public-IP+ can't run anywhere, neither can +Email+; * but if +Email+ can't run anywhere, this does not affect +Public-IP+ in any way The group above is logically equivalent to writing: .How the cluster sees a group resource +====== [source,XML] ------- ------- +====== Obviously as the group grows bigger, the reduced configuration effort can become significant. Another (typical) example of a group is a DRBD volume, the filesystem mount, an IP address, and an application that uses them. === Group Properties === .Properties of a Group Resource [width="95%",cols="3m,5<",options="header",align="center"] |========================================================= |Field |Description |id |Your name for the group indexterm:[id,Group Resource Property] indexterm:[Group Resource Properties,id] indexterm:[Resource,Group Property,id] |========================================================= === Group Options === Options inherited from xref:s-resource-options[]: +priority, target-role, is-managed+ === Group Instance Attributes === Groups have no instance attributes, however any that are set here will be inherited by the group's children. === Group Contents === Groups may only contain a collection of xref:primitive-resource[] cluster resources. To refer to the child of a group resource, just use the child's id instead of the group's. === Group Constraints === Although it is possible to reference the group's children in constraints, it is usually preferable to use the group's name instead. .Example constraints involving groups +====== [source,XML] ------- ------- +====== === Group Stickiness === indexterm:[resource-stickiness,of a Group Resource] Stickiness, the measure of how much a resource wants to stay where it is, is additive in groups. Every active resource of the group will contribute its stickiness value to the group's total. So if the default +resource-stickiness+ is 100, and a group has seven members, five of which are active, then the group as a whole will prefer its current location with a score of 500. == Clones - Resources That Get Active on Multiple Hosts == indexterm:[Clone Resources] indexterm:[Resources,Clones] anchor:s-resource-clone[Clone Resources] Clones were initially conceived as a convenient way to start N instances of an IP resource and have them distributed throughout the cluster for load balancing. They have turned out to quite useful for a number of purposes including integrating with Red Hat's DLM, the fencing subsystem, and OCFS2. You can clone any resource, provided the resource agent supports it. Three types of cloned resources exist: * Anonymous * Globally Unique * Stateful Anonymous clones are the simplest type. These resources behave completely identically everywhere they are running. Because of this, there can only be one copy of an anonymous clone active per machine. Globally unique clones are distinct entities. A copy of the clone running on one machine is not equivalent to another instance on another node. Nor would any two copies on the same node be equivalent. Stateful clones are covered later in xref:s-resource-multistate[]. .An example clone +====== [source,XML] ------- ------- +====== === Clone Properties === .Properties of a Clone Resource [width="95%",cols="3m,5<",options="header",align="center"] |========================================================= |Field |Description |id |Your name for the clone indexterm:[id,Clone Resource Property] indexterm:[Clone Resource Properties,id] indexterm:[Resource,Clone Property,id] |========================================================= === Clone Options === Options inherited from xref:s-resource-options[] resources: +priority, target-role, is-managed+ .Clone specific configuration options [width="95%",cols="3m,5<",options="header",align="center"] |========================================================= |Field |Description |clone-max |How many copies of the resource to start. Defaults to the number of nodes in the cluster. indexterm:[clone-max Clone Resource Property] indexterm:[Clone Resource Properties,clone-max] indexterm:[Resource,Clone Property,clone-max] |clone-node-max |How many copies of the resource can be started on a single node; default _1_. indexterm:[clone-node-max Clone Resource Property] indexterm:[Clone Resource Properties,clone-node-max] indexterm:[Resource,Clone Property,clone-node-max] |notify |When stopping or starting a copy of the clone, tell all the other copies beforehand and when the action was successful. Allowed values: _false_, +true+ indexterm:[notify Clone Resource Property] indexterm:[Clone Resource Properties,notify] indexterm:[Resource,Clone Property,notify] |globally-unique |Does each copy of the clone perform a different function? Allowed values: _false_, +true+ indexterm:[globally-unique Clone Resource Property] indexterm:[Clone Resource Properties,globally-unique] indexterm:[Resource,Clone Property,globally-unique] |ordered |Should the copies be started in series (instead of in parallel). Allowed values: _false_, +true+ indexterm:[ordered Clone Resource Property] indexterm:[Clone Resource Properties,ordered] indexterm:[Resource,Clone Property,ordered] |interleave |Changes the behavior of ordering constraints (between clones/masters) so that instances can start/stop as soon as their peer instance has (rather than waiting for every instance of the other clone has). Allowed values: _false_, +true+ indexterm:[interleave Clone Resource Property] indexterm:[Clone Resource Properties,interleave] indexterm:[Resource,Clone Property,interleave] |========================================================= === Clone Instance Attributes === Clones have no instance attributes; however, any that are set here will be inherited by the clone's children. === Clone Contents === Clones must contain exactly one group or one regular resource. [WARNING] You should never reference the name of a clone's child. If you think you need to do this, you probably need to re-evaluate your design. === Clone Constraints === In most cases, a clone will have a single copy on each active cluster node. If this is not the case, you can indicate which nodes the cluster should preferentially assign copies to with resource location constraints. These constraints are written no differently to those for regular resources except that the clone's id is used. Ordering constraints behave slightly differently for clones. In the example below, +apache-stats+ will wait until all copies of the clone that need to be started have done so before being started itself. Only if _no_ copies can be started +apache-stats+ will be prevented from being active. Additionally, the clone will wait for +apache-stats+ to be stopped before stopping the clone. Colocation of a regular (or group) resource with a clone means that the resource can run on any machine with an active copy of the clone. The cluster will choose a copy based on where the clone is running and the resource's own location preferences. Colocation between clones is also possible. In such cases, the set of allowed locations for the clone is limited to nodes on which the clone is (or will be) active. Allocation is then performed as normally. .Example constraints involving clones +====== [source,XML] ------- ------- +====== === Clone Stickiness === indexterm:[resource-stickiness,of a Clone Resource] To achieve a stable allocation pattern, clones are slightly sticky by default. If no value for +resource-stickiness+ is provided, the clone will use a value of 1. Being a small value, it causes minimal disturbance to the score calculations of other resources but is enough to prevent Pacemaker from needlessly moving copies around the cluster. === Clone Resource Agent Requirements === Any resource can be used as an anonymous clone, as it requires no additional support from the resource agent. Whether it makes sense to do so depends on your resource and its resource agent. Globally unique clones do require some additional support in the resource agent. In particular, it must only respond with +${OCF_SUCCESS}+ if the node has that exact instance active. All other probes for instances of the clone should result in +${OCF_NOT_RUNNING}+. Unless of course they are failed, in which case they should return one of the other OCF error codes. Copies of a clone are identified by appending a colon and a numerical offset, eg. +apache:2+. Resource agents can find out how many copies there are by examining the +OCF_RESKEY_CRM_meta_clone_max+ environment variable and which copy it is by examining +OCF_RESKEY_CRM_meta_clone+. You should not make any assumptions (based on +OCF_RESKEY_CRM_meta_clone+) about which copies are active. In particular, the list of active copies will not always be an unbroken sequence, nor always start at 0. ==== Clone Notifications ==== Supporting notifications requires the +notify+ action to be implemented. Once supported, the notify action will be passed a number of extra variables which, when combined with additional context, can be used to calculate the current state of the cluster and what is about to happen to it. .Environment variables supplied with Clone notify actions [width="95%",cols="5,3<",options="header",align="center"] |========================================================= |Variable |Description |OCF_RESKEY_CRM_meta_notify_type |Allowed values: +pre+, +post+ indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_type] indexterm:[OCF_RESKEY_CRM_,meta_notify_type] |OCF_RESKEY_CRM_meta_notify_operation |Allowed values: +start+, +stop+ indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_operation] indexterm:[OCF_RESKEY_CRM_,meta_notify_operation] |OCF_RESKEY_CRM_meta_notify_start_resource |Resources to be started indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_start_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_start_resource] |OCF_RESKEY_CRM_meta_notify_stop_resource |Resources to be stopped indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_stop_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_stop_resource] |OCF_RESKEY_CRM_meta_notify_active_resource |Resources that are running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_active_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_active_resource] |OCF_RESKEY_CRM_meta_notify_inactive_resource |Resources that are not running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_inactive_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_inactive_resource] |OCF_RESKEY_CRM_meta_notify_start_uname |Nodes on which resources will be started indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_start_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_start_uname] |OCF_RESKEY_CRM_meta_notify_stop_uname |Nodes on which resources will be stopped indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_stop_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_stop_uname] |OCF_RESKEY_CRM_meta_notify_active_uname |Nodes on which resources are running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_active_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_active_uname] |OCF_RESKEY_CRM_meta_notify_inactive_uname |Nodes on which resources are not running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_inactive_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_inactive_uname] |========================================================= The variables come in pairs, such as +OCF_RESKEY_CRM_meta_notify_start_resource+ and +OCF_RESKEY_CRM_meta_notify_start_uname+ and should be treated as an array of whitespace separated elements. Thus in order to indicate that +clone:0+ will be started on +sles-1+, +clone:2+ will be started on +sles-3+, and +clone:3+ will be started on +sles-2+, the cluster would set .Example notification variables +====== [source,Bash] ------- -OCF_RESKEY_CRM_meta_notify_start_resource+="clone:0 clone:2 clone:3" -OCF_RESKEY_CRM_meta_notify_start_uname+="sles-1 sles-3 sles-2" +OCF_RESKEY_CRM_meta_notify_start_resource="clone:0 clone:2 clone:3" +OCF_RESKEY_CRM_meta_notify_start_uname="sles-1 sles-3 sles-2" ------- +====== ==== Proper Interpretation of Notification Environment Variables ==== .Pre-notification (stop): * Active resources: +$OCF_RESKEY_CRM_meta_notify_active_resource+ * Inactive resources: +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ * Resources to be started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ .Post-notification (stop) / Pre-notification (start): * Active resources ** +$OCF_RESKEY_CRM_meta_notify_active_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Inactive resources ** +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Resources that were started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources that were stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ .Post-notification (start): * Active resources: ** +$OCF_RESKEY_CRM_meta_notify_active_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Inactive resources: ** +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources that were started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources that were stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ == Multi-state - Resources That Have Multiple Modes == indexterm:[Multi-state Resources] indexterm:[Resources,Multi-state] anchor:s-resource-multistate[Multi-state Resources] Multi-state resources are a specialization of Clone resources; please ensure you understand the section on clones before continuing! They allow the instances to be in one of two operating modes; these are called +Master+ and +Slave+, but can mean whatever you wish them to mean. The only limitation is that when an instance is started, it must come up in the +Slave+ state. === Multi-state Properties === .Properties of a Multi-State Resource [width="95%",cols="3m,5<",options="header",align="center"] |========================================================= |Field |Description |id |Your name for the multi-state resource indexterm:[id,Multi-State Resource Property] indexterm:[Multi-State Resource Properties,id] indexterm:[Resource,Multi-State Property,id] |========================================================= === Multi-state Options === Options inherited from xref:s-resource-options[] resources: +priority+, +target-role+, +is-managed+ Options inherited from xref:s-resource-clone[]: +clone-max+, +clone-node-max+, +notify+, +globally-unique+, +ordered+, +interleave+ .Multi-state specific resource configuration options [width="95%",cols="3m,5<",options="header",align="center"] |========================================================= |Field |Description |master-max |How many copies of the resource can be promoted to +master+ status; default 1. indexterm:[master-max Multi-State Resource Property] indexterm:[Multi-State Resource Properties,master-max] indexterm:[Resource,Multi-State Property,master-max] |master-node-max |How many copies of the resource can be promoted to +master+ status on a single node; default 1. indexterm:[master-node-max Multi-State Resource Property] indexterm:[Multi-State Resource Properties,master-node-max] indexterm:[Resource,Multi-State Property,master-node-max] |========================================================= === Multi-state Instance Attributes === Multi-state resources have no instance attributes; however, any that are set here will be inherited by master's children. === Multi-state Contents === Masters must contain exactly one group or one regular resource. [WARNING] You should never reference the name of a master's child. If you think you need to do this, you probably need to re-evaluate your design. === Monitoring Multi-State Resources === The normal type of monitor actions are not sufficient to monitor a multi-state resource in the +Master+ state. To detect failures of the +Master+ instance, you need to define an additional monitor action with +role="Master"+. [IMPORTANT] =========== It is crucial that _every_ monitor operation has a different interval! This is because Pacemaker currently differentiates between operations only by resource and interval; so if eg. a master/slave resource has the same monitor interval for both roles, Pacemaker would ignore the role when checking the status - which would cause unexpected return codes, and therefore unnecessary complications. =========== .Monitoring both states of a multi-state resource +====== [source,XML] ------- ------- +====== + === Multi-state Constraints === In most cases, a multi-state resources will have a single copy on each active cluster node. If this is not the case, you can indicate which nodes the cluster should preferentially assign copies to with resource location constraints. These constraints are written no differently to those for regular resources except that the master's id is used. When considering multi-state resources in constraints, for most purposes it is sufficient to treat them as clones. The exception is when the +rsc-role+ and/or +with-rsc-role+ fields (for colocation constraints) and +first-action+ and/or +then-action+ fields (for ordering constraints) are used. .Additional constraint options relevant to multi-state resources [width="95%",cols="3m,5<",options="header",align="center"] |========================================================= |Field |Description |rsc-role |An additional attribute of colocation constraints that specifies the role that +rsc+ must be in. Allowed values: _Started_, +Master+, +Slave+. indexterm:[rsc-role Multi-State Resource Constraints] indexterm:[Multi-State Resource Constraints,rsc-role] indexterm:[Resource,Multi-State Constraints,rsc-role] |with-rsc-role |An additional attribute of colocation constraints that specifies the role that +with-rsc+ must be in. Allowed values: _Started_, +Master+, +Slave+. indexterm:[with-rsc-role Multi-State Resource Constraints] indexterm:[Multi-State Resource Constraints,with-rsc-role] indexterm:[Resource,Multi-State Constraints,with-rsc-role] |first-action |An additional attribute of ordering constraints that specifies the action that the +first+ resource must complete before executing the specified action for the +then+ resource. Allowed values: _start_, +stop+, +promote+, +demote+. indexterm:[first-action Multi-State Resource Constraints] indexterm:[Multi-State Resource Constraints,first-action] indexterm:[Resource,Multi-State Constraints,first-action] |then-action |An additional attribute of ordering constraints that specifies the action that the +then+ resource can only execute after the +first-action+ on the +first+ resource has completed. Allowed values: +start+, +stop+, +promote+, +demote+. Defaults to the value (specified or implied) of +first-action+. indexterm:[then-action Multi-State Resource Constraints] indexterm:[Multi-State Resource Constraints,then-action] indexterm:[Resource,Multi-State Constraints,then-action] |========================================================= In the example below, +myApp+ will wait until one of the database copies has been started and promoted to master before being started itself. Only if no copies can be promoted will +apache-stats+ be prevented from being active. Additionally, the database will wait for +myApp+ to be stopped before it is demoted. .Example constraints involving multi-state resources +====== [source,XML] ------- ------- +====== Colocation of a regular (or group) resource with a multi-state resource means that it can run on any machine with an active copy of the multi-state resource that is in the specified state (+Master+ or +Slave+). In the example, the cluster will choose a location based on where database is running as a +Master+, and if there are multiple +Master+ instances it will also factor in +myApp+'s own location preferences when deciding which location to choose. Colocation with regular clones and other multi-state resources is also possible. In such cases, the set of allowed locations for the +rsc+ clone is (after role filtering) limited to nodes on which the +with-rsc+ multi-state resource is (or will be) in the specified role. Allocation is then performed as-per-normal. === Multi-state Stickiness === indexterm:[resource-stickiness,of a Multi-State Resource] To achieve a stable allocation pattern, multi-state resources are slightly sticky by default. If no value for +resource-stickiness+ is provided, the multi-state resource will use a value of 1. Being a small value, it causes minimal disturbance to the score calculations of other resources but is enough to prevent Pacemaker from needlessly moving copies around the cluster. === Which Resource Instance is Promoted === During the start operation, most Resource Agent scripts should call the `crm_master` utility. This tool automatically detects both the resource and host and should be used to set a preference for being promoted. Based on this, +master-max+, and +master-node-max+, the instance(s) with the highest preference will be promoted. The other alternative is to create a location constraint that indicates which nodes are most preferred as masters. .Manually specifying which node should be promoted +====== [source,XML] ------- ------- +====== === Multi-state Resource Agent Requirements === Since multi-state resources are an extension of cloned resources, all the requirements of Clones are also requirements of multi-state resources. Additionally, multi-state resources require two extra actions: +demote+ and +promote+; these actions are responsible for changing the state of the resource. Like +start+ and +stop+, they should return +OCF_SUCCESS+ if they completed successfully or a relevant error code if they did not. The states can mean whatever you wish, but when the resource is started, it must come up in the mode called +Slave+. From there the cluster will then decide which instances to promote to +Master+. In addition to the Clone requirements for monitor actions, agents must also _accurately_ report which state they are in. The cluster relies on the agent to report its status (including role) accurately and does not indicate to the agent what role it currently believes it to be in. .Role implications of OCF return codes [width="95%",cols="5,3<",options="header",align="center"] |========================================================= |Monitor Return Code |Description |OCF_NOT_RUNNING |Stopped indexterm:[return code,OCF_NOT_RUNNING] indexterm:[Environment Variable,OCF_NOT_RUNNING] indexterm:[OCF_NOT_RUNNING] |OCF_SUCCESS |Running (Slave) indexterm:[return code,OCF_SUCCESS] indexterm:[Environment Variable,OCF_SUCCESS] indexterm:[OCF_SUCCESS] |OCF_RUNNING_MASTER |Running (Master) indexterm:[return code,OCF_RUNNING_MASTER] indexterm:[Environment Variable,OCF_RUNNING_MASTER] indexterm:[OCF_RUNNING_MASTER] |OCF_FAILED_MASTER |Failed (Master) indexterm:[return code,OCF_FAILED_MASTER] indexterm:[Environment Variable,OCF_FAILED_MASTER] indexterm:[OCF_FAILED_MASTER] |Other |Failed (Slave) |========================================================= === Multi-state Notifications === Like clones, supporting notifications requires the +notify+ action to be implemented. Once supported the notify action will be passed a number of extra variables which, when combined with additional context, can be used to calculate the current state of the cluster and what is about to happen to it. .Environment variables supplied with Master notify actions footnote:[Emphasized variables are specific to +Master+ resources and all behave in the same manner as described for Clone resources.] [width="95%",cols="5,3<",options="header",align="center"] |========================================================= |Variable |Description |OCF_RESKEY_CRM_meta_notify_type |Allowed values: +pre+, +post+ indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_type] indexterm:[OCF_RESKEY_CRM_,meta_notify_type] |OCF_RESKEY_CRM_meta_notify_operation |Allowed values: +start+, +stop+ indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_operation] indexterm:[OCF_RESKEY_CRM_,meta_notify_operation] |OCF_RESKEY_CRM_meta_notify_active_resource |Resources the that are running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_active_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_active_resource] |OCF_RESKEY_CRM_meta_notify_inactive_resource |Resources the that are not running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_inactive_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_inactive_resource] |_OCF_RESKEY_CRM_meta_notify_master_resource_ |Resources that are running in +Master+ mode indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_master_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_master_resource] |_OCF_RESKEY_CRM_meta_notify_slave_resource_ |Resources that are running in +Slave+ mode indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_slave_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_slave_resource] |OCF_RESKEY_CRM_meta_notify_start_resource |Resources to be started indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_start_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_start_resource] |indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_stop_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_stop_resource] OCF_RESKEY_CRM_meta_notify_stop_resource |Resources to be stopped |_OCF_RESKEY_CRM_meta_notify_promote_resource_ |Resources to be promoted indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_promote_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_promote_resource] |_OCF_RESKEY_CRM_meta_notify_demote_resource_ |Resources to be demoted indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_demote_resource] indexterm:[OCF_RESKEY_CRM_,meta_notify_demote_resource] |OCF_RESKEY_CRM_meta_notify_start_uname |Nodes on which resources will be started indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_start_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_start_uname] |OCF_RESKEY_CRM_meta_notify_stop_uname |Nodes on which resources will be stopped indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_stop_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_stop_uname] |_OCF_RESKEY_CRM_meta_notify_promote_uname_ |Nodes on which resources will be promote indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_promote_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_promote_uname] |_OCF_RESKEY_CRM_meta_notify_demote_uname_ |Nodes on which resources will be demoted indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_demote_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_demote_uname] |OCF_RESKEY_CRM_meta_notify_active_uname |Nodes on which resources are running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_active_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_active_uname] |OCF_RESKEY_CRM_meta_notify_inactive_uname |Nodes on which resources are not running indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_inactive_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_inactive_uname] |_OCF_RESKEY_CRM_meta_notify_master_uname_ |Nodes on which resources are running in +Master+ mode indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_master_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_master_uname] |_OCF_RESKEY_CRM_meta_notify_slave_uname_ |Nodes on which resources are running in +Slave+ mode indexterm:[Environment Variable,OCF_RESKEY_CRM_,meta_notify_slave_uname] indexterm:[OCF_RESKEY_CRM_,meta_notify_slave_uname] |========================================================= === Multi-state - Proper Interpretation of Notification Environment Variables === .Pre-notification (demote): * +Active+ resources: +$OCF_RESKEY_CRM_meta_notify_active_resource+ * +Master+ resources: +$OCF_RESKEY_CRM_meta_notify_master_resource+ * +Slave+ resources: +$OCF_RESKEY_CRM_meta_notify_slave_resource+ * Inactive resources: +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ * Resources to be started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be promoted: +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * Resources to be demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources to be stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ .Post-notification (demote) / Pre-notification (stop): * +Active+ resources: +$OCF_RESKEY_CRM_meta_notify_active_resource+ * +Master+ resources: ** +$OCF_RESKEY_CRM_meta_notify_master_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * +Slave+ resources: +$OCF_RESKEY_CRM_meta_notify_slave_resource+ * Inactive resources: +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ * Resources to be started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be promoted: +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * Resources to be demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources to be stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Resources that were demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ .Post-notification (stop) / Pre-notification (start) * +Active+ resources: ** +$OCF_RESKEY_CRM_meta_notify_active_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * +Master+ resources: ** +$OCF_RESKEY_CRM_meta_notify_master_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * +Slave+ resources: ** +$OCF_RESKEY_CRM_meta_notify_slave_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Inactive resources: ** +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Resources to be started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be promoted: +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * Resources to be demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources to be stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Resources that were demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources that were stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ .Post-notification (start) / Pre-notification (promote) * +Active+ resources: ** +$OCF_RESKEY_CRM_meta_notify_active_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_start_resource+ * +Master+ resources: ** +$OCF_RESKEY_CRM_meta_notify_master_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * +Slave+ resources: ** +$OCF_RESKEY_CRM_meta_notify_slave_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Inactive resources: ** +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be promoted: +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * Resources to be demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources to be stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Resources that were started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources that were demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources that were stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ .Post-notification (promote) * +Active+ resources: ** +$OCF_RESKEY_CRM_meta_notify_active_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_start_resource+ * +Master+ resources: ** +$OCF_RESKEY_CRM_meta_notify_master_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_demote_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * +Slave+ resources: ** +$OCF_RESKEY_CRM_meta_notify_slave_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_start_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * Inactive resources: ** +$OCF_RESKEY_CRM_meta_notify_inactive_resource+ ** plus +$OCF_RESKEY_CRM_meta_notify_stop_resource+ ** minus +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources to be promoted: +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * Resources to be demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources to be stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ * Resources that were started: +$OCF_RESKEY_CRM_meta_notify_start_resource+ * Resources that were promoted: +$OCF_RESKEY_CRM_meta_notify_promote_resource+ * Resources that were demoted: +$OCF_RESKEY_CRM_meta_notify_demote_resource+ * Resources that were stopped: +$OCF_RESKEY_CRM_meta_notify_stop_resource+ diff --git a/doc/Pacemaker_Explained/en-US/Ch-Basics.txt b/doc/Pacemaker_Explained/en-US/Ch-Basics.txt index c165dcdf39..8f4bfa14d6 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Basics.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Basics.txt @@ -1,349 +1,368 @@ = Configuration Basics = == Configuration Layout == The cluster is written using XML notation and divided into two main sections: configuration and status. The status section contains the history of each resource on each node and based on this data, the cluster can construct the complete current state of the cluster. The authoritative source for the status section is the local resource manager (lrmd) process on each cluster node and the cluster will occasionally repopulate the entire section. For this reason it is never written to disk and administrators are advised against modifying it in any way. The configuration section contains the more traditional information like cluster options, lists of resources and indications of where they should be placed. The configuration section is the primary focus of this document. The configuration section itself is divided into four parts: * Configuration options (called +crm_config+) * Nodes * Resources * Resource relationships (called +constraints+) .An empty configuration +====== [source,XML] ------- ------- +====== == The Current State of the Cluster == Before one starts to configure a cluster, it is worth explaining how to view the finished product. For this purpose we have created the `crm_mon` utility that will display the current state of an active cluster. It can show the cluster status by node or by resource and can be used in either single-shot or dynamically-updating mode. There are also modes for displaying a list of the operations performed (grouped by node and resource) as well as information about failures. Using this tool, you can examine the state of the cluster for irregularities and see how it responds when you cause or simulate failures. Details on all the available options can be obtained using the `crm_mon --help` command. .Sample output from crm_mon +====== ------- ============ Last updated: Fri Nov 23 15:26:13 2007 Current DC: sles-3 (2298606a-6a8c-499a-9d25-76242f7006ec) 3 Nodes configured. 5 Resources configured. ============ Node: sles-1 (1186dc9a-324d-425a-966e-d757e693dc86): online 192.168.100.181 (heartbeat::ocf:IPaddr): Started sles-1 192.168.100.182 (heartbeat:IPaddr): Started sles-1 192.168.100.183 (heartbeat::ocf:IPaddr): Started sles-1 rsc_sles-1 (heartbeat::ocf:IPaddr): Started sles-1 child_DoFencing:2 (stonith:external/vmware): Started sles-1 Node: sles-2 (02fb99a8-e30e-482f-b3ad-0fb3ce27d088): standby Node: sles-3 (2298606a-6a8c-499a-9d25-76242f7006ec): online rsc_sles-2 (heartbeat::ocf:IPaddr): Started sles-3 rsc_sles-3 (heartbeat::ocf:IPaddr): Started sles-3 child_DoFencing:0 (stonith:external/vmware): Started sles-3 ------- +====== .Sample output from crm_mon -n +====== ------- ============ Last updated: Fri Nov 23 15:26:13 2007 Current DC: sles-3 (2298606a-6a8c-499a-9d25-76242f7006ec) 3 Nodes configured. 5 Resources configured. ============ Node: sles-1 (1186dc9a-324d-425a-966e-d757e693dc86): online Node: sles-2 (02fb99a8-e30e-482f-b3ad-0fb3ce27d088): standby Node: sles-3 (2298606a-6a8c-499a-9d25-76242f7006ec): online Resource Group: group-1 192.168.100.181 (heartbeat::ocf:IPaddr): Started sles-1 192.168.100.182 (heartbeat:IPaddr): Started sles-1 192.168.100.183 (heartbeat::ocf:IPaddr): Started sles-1 rsc_sles-1 (heartbeat::ocf:IPaddr): Started sles-1 rsc_sles-2 (heartbeat::ocf:IPaddr): Started sles-3 rsc_sles-3 (heartbeat::ocf:IPaddr): Started sles-3 Clone Set: DoFencing child_DoFencing:0 (stonith:external/vmware): Started sles-3 child_DoFencing:1 (stonith:external/vmware): Stopped child_DoFencing:2 (stonith:external/vmware): Started sles-1 ------- +====== The DC (Designated Controller) node is where all the decisions are made and if the current DC fails a new one is elected from the remaining cluster nodes. The choice of DC is of no significance to an administrator beyond the fact that its logs will generally be more interesting. == How Should the Configuration be Updated? == There are three basic rules for updating the cluster configuration: * Rule 1 - Never edit the cib.xml file manually. Ever. I'm not making this up. * Rule 2 - Read Rule 1 again. * Rule 3 - The cluster will notice if you ignored rules 1 & 2 and refuse to use the configuration. Now that it is clear how NOT to update the configuration, we can begin to explain how you should. The most powerful tool for modifying the configuration is the +cibadmin+ command which talks to a running cluster. With +cibadmin+, the user can query, add, remove, update or replace any part of the configuration; all changes take effect immediately, so there is no need to perform a reload-like operation. The simplest way of using cibadmin is to use it to save the current configuration to a temporary file, edit that file with your favorite text or XML editor and then upload the revised configuration. .Safely using an editor to modify the cluster configuration -[source,Bash] +====== +[source,C] -------- # cibadmin --query > tmp.xml # vi tmp.xml # cibadmin --replace --xml-file tmp.xml -------- +====== Some of the better XML editors can make use of a Relax NG schema to help make sure any changes you make are valid. The schema describing the configuration can normally be found in pass:[/usr/lib/heartbeat/pacemaker.rng] on most systems. If you only wanted to modify the resources section, you could instead do .Safely using an editor to modify a subsection of the cluster configuration -[source,Bash] +====== +[source,C] -------- # cibadmin --query --obj_type resources > tmp.xml # vi tmp.xml # cibadmin --replace --obj_type resources --xml-file tmp.xml -------- +====== to avoid modifying any other part of the configuration. == Quickly Deleting Part of the Configuration == Identify the object you wish to delete. Eg. run .Searching for STONITH related configuration items -[source,Bash] +====== +[source,C] -------- # cibadmin -Q | grep stonith -------- +====== Next identify the resource's tag name and id (in this case we'll choose +primitive+ and +child_DoFencing+). Then simply execute: `cibadmin --delete --crm_xml '<primitive id="child_DoFencing"/>'` == Updating the Configuration Without Using XML == Some common tasks can also be performed with one of the higher level tools that avoid the need to read or edit XML. To enable stonith for example, one could run: -`crm_attribute --attr-name stonith-enabled --attr-value true` +[source,C] +# crm_attribute --attr-name stonith-enabled --attr-value true Or, to see if +somenode+ is allowed to run resources, there is: -`crm_standby --get-value --node-uname somenode` +[source,C] +# crm_standby --get-value --node-uname somenode Or, to find the current location of +my-test-rsc+, one can use: -`crm_resource --locate --resource my-test-rsc` +[source,C] +# crm_resource --locate --resource my-test-rsc [[s-config-sandboxes]] == Making Configuration Changes in a Sandbox == Often it is desirable to preview the effects of a series of changes before updating the configuration atomically. For this purpose we have created `crm_shadow` which creates a "shadow" copy of the configuration and arranges for all the command line tools to use it. To begin, simply invoke `crm_shadow` and give it the name of a configuration to create footnote:[Shadow copies are identified with a name, making it possible to have more than one.] ; be sure to follow the simple on-screen instructions. WARNING: Read the above carefully, failure to do so could result in you destroying the cluster's active configuration! .Creating and displaying the active sandbox [source,Bash] +====== -------- # crm_shadow --create test Setting up shadow instance Type Ctrl-D to exit the crm_shadow shell shadow[test]: shadow[test] # crm_shadow --which test -------- +====== From this point on, all cluster commands will automatically use the shadow copy instead of talking to the cluster's active configuration. Once you have finished experimenting, you can either commit the changes, or discard them as shown below. Again, be sure to follow the on-screen instructions carefully. For a full list of `crm_shadow` options and commands, invoke it with the --help option. .Using a sandbox to make multiple changes atomically +====== [source,Bash] -------- shadow[test] # crm_failcount -G -r rsc_c001n01 name=fail-count-rsc_c001n01 value=0 shadow[test] # crm_standby -v on -n c001n02 shadow[test] # crm_standby -G -n c001n02 name=c001n02 scope=nodes value=on shadow[test] # cibadmin --erase --force shadow[test] # cibadmin --query shadow[test] # crm_shadow --delete test --force Now type Ctrl-D to exit the crm_shadow shell shadow[test] # exit # crm_shadow --which No shadow instance provided # cibadmin -Q -------- +====== Making changes in a sandbox and verifying the real configuration is untouched [[s-config-testing-changes]] == Testing Your Configuration Changes == - We saw previously how to make a series of changes to a "shadow" copy of the configuration. Before loading the changes back into the -cluster (eg. `crm_shadow --commit mytest ---force`), it is often advisable to simulate the effect of -the changes with +crm_simulate+, eg. +cluster (eg. `crm_shadow --commit mytest --force`), it is often +advisable to simulate the effect of the changes with +crm_simulate+, +eg. -`crm_simulate --live-check -VVVVV --save-graph tmp.graph --save-dotfile tmp.dot` +[source,C] +# crm_simulate --live-check -VVVVV --save-graph tmp.graph --save-dotfile tmp.dot The tool uses the same library as the live cluster to show what it would have done given the supplied input. It's output, in addition to a significant amount of logging, is stored in two files +tmp.graph+ and +tmp.dot+, both are representations of the same thing -- the cluster's response to your changes. In the graph file is stored the complete transition, containing a list of all the actions, their parameters and their pre-requisites. Because the transition graph is not terribly easy to read, the tool also generates a Graphviz dot-file representing the same information. == Interpreting the Graphviz output == * Arrows indicate ordering dependencies * Dashed-arrows indicate dependencies that are not present in the transition graph * Actions with a dashed border of any color do not form part of the transition graph * Actions with a green border form part of the transition graph * Actions with a red border are ones the cluster would like to execute but cannot run * Actions with a blue border are ones the cluster does not feel need to be executed * Actions with orange text are pseudo/pretend actions that the cluster uses to simplify the graph * Actions with black text are sent to the LRM * Resource actions have text of the form pass:[rsc]_pass:[action]_pass:[interval] pass:[node] * Any action depending on an action with a red border will not be able to execute. * Loops are _really_ bad. Please report them to the development team. === Small Cluster Transition === image::images/Policy-Engine-small.png["An example transition graph as represented by Graphviz",width="16cm",height="6cm",align="center"] In the above example, it appears that a new node, +node2+, has come online and that the cluster is checking to make sure +rsc1+, +rsc2+ and +rsc3+ are not already running there (Indicated by the +*_monitor_0+ entries). Once it did that, and assuming the resources were not active there, it would have liked to stop +rsc1+ and +rsc2+ on +node1+ and move them to +node2+. However, there appears to be some problem and the cluster cannot or is not permitted to perform the stop actions which implies it also cannot perform the start actions. For some reason the cluster does not want to start +rsc3+ anywhere. For information on the options supported by `crm_simulate`, use the `--help` option. === Complex Cluster Transition === image::images/Policy-Engine-big.png["Another, slightly more complex, transition graph that you're not expected to be able to read",width="16cm",height="20cm",align="center"] == Do I Need to Update the Configuration on all Cluster Nodes? == No. Any changes are immediately synchronized to the other active members of the cluster. To reduce bandwidth, the cluster only broadcasts the incremental updates that result from your changes and uses MD5 checksums to ensure that each copy is completely consistent. diff --git a/doc/Pacemaker_Explained/en-US/Ch-Constraints.txt b/doc/Pacemaker_Explained/en-US/Ch-Constraints.txt index e93edd1adc..677f96ed0c 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Constraints.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Constraints.txt @@ -1,546 +1,572 @@ = Resource Constraints = == Scores == indexterm:[Resource,Constraints] indexterm:[Constraints,for Resources] Scores of all kinds are integral to how the cluster works. Practically everything from moving a resource to deciding which resource to stop in a degraded cluster is achieved by manipulating scores in some way. Scores are calculated on a per-resource basis and any node with a negative score for a resource can't run that resource. After calculating the scores for a resource, the cluster then chooses the node with the highest one. === Infinity Math === +INFINITY+ is currently defined as 1,000,000 and addition/subtraction with it follows these three basic rules: * Any value + +INFINITY+ = +INFINITY+ * Any value - +INFINITY+ = -+INFINITY+ * +INFINITY+ - +INFINITY+ = -+INFINITY+ == Deciding Which Nodes a Resource Can Run On == There are two alternative strategies for specifying which nodes a resources can run on. One way is to say that by default they can run anywhere and then create location constraints for nodes that are not allowed. The other option is to have nodes "opt-in"... to start with nothing able to run anywhere and selectively enable allowed nodes. === Options === .Options for Simple Location Constraints [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |id indexterm:[id,Constraint Field] indexterm:[Constraint Field,id] |A unique name for the constraint |rsc, indexterm:[rsc Constraint Field] indexterm:[Constraint Field,rsc] |A resource name |node indexterm:[Node,Constraint Field] indexterm:[Constraint Field,node] |A node's uname |score indexterm:[score,Constraint Field] indexterm:[Constraint Field,score] |Positive values indicate the resource should run on this . node. Negative values indicate the resource should not run on this node. Values of +/- +INFINITY+ change "should"/"should not" to "must"/"must not". |========================================================= === Asymmetrical "Opt-In" Clusters === indexterm:[Asymmetrical Opt-In Clusters] indexterm:[Cluster Type,Asymmetrical Opt-In] To create an opt-in cluster, start by preventing resources from running anywhere by default: -[source,Bash] -crm_attribute --attr-name symmetric-cluster --attr-value false +[source,C] +# crm_attribute --attr-name symmetric-cluster --attr-value false Then start enabling nodes. The following fragment says that the web server prefers +sles-1+, the database prefers +sles-2+ and both can fail over to +sles-3+ if their most preferred node fails. .Example set of opt-in location constraints +====== [source,XML] ------- ------- +====== === Symmetrical "Opt-Out" Clusters === indexterm:[Symmetrical Opt-Out Clusters] indexterm:[Cluster Type,Symmetrical Opt-Out] To create an opt-out cluster, start by allowing resources to run anywhere by default: -[source,Bash] -crm_attribute --attr-name symmetric-cluster --attr-value true +[source,C] +# crm_attribute --attr-name symmetric-cluster --attr-value true Then start disabling nodes. The following fragment is the equivalent of the above opt-in configuration. .Example set of opt-out location constraints +====== [source,XML] ------- ------- +====== Whether you should choose opt-in or opt-out depends both on your personal preference and the make-up of your cluster. If most of your resources can run on most of the nodes, then an opt-out arrangement is likely to result in a simpler configuration. On the other-hand, if most resources can only run on a small subset of nodes an opt-in configuration might be simpler. === What if Two Nodes Have the Same Score === anchor:node-score-equal[What if Two Nodes Have the Same Score] If two nodes have the same score, then the cluster will choose one. This choice may seem random and may not be what was intended, however the cluster was not given enough information to know any better. .Example of two resources that prefer two nodes equally +====== [source,XML] ------- ------- +====== In the example above, assuming no other constraints and an inactive cluster, Webserver would probably be placed on sles-1 and Database on sles-2. It would likely have placed Webserver based on the node's uname and Database based on the desire to spread the resource load evenly across the cluster. However other factors can also be involved in more complex configurations. == Specifying in which Order Resources Should Start/Stop == anchor:s-resource-ordering[Resource Start Ordering] The way to specify the order in which resources should start is by creating +rsc_order+ constraints. .Properties of an Ordering Constraint [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |id |A unique name for the constraint |first |The name of a resource that must be started before the +then+ resource is allowed to. |then |The name of a resource. This resource will start after the +first+ resource. |score |If greater than zero, the constraint is mandatory. Otherwise it is only a suggestion. Default value: _INFINITY_ |symmetrical |If true, which is the default, stop the resources in the reverse order. Default value: _true_ |========================================================= === Mandatory Ordering === When the +then+ resource cannot run without the +first+ resource being active, one should use mandatory constraints. To specify a constraint is mandatory, use scores greater than zero. This will ensure that the then resource will react when the first resource changes state. * If the +first+ resource was running and is stopped, the +then+ resource will also be stopped (if it is running). * If the +first+ resource was not running and cannot be started, the +then+ resource will be stopped (if it is running). * If the +first+ resource is (re)started while the +then+ resource is running, the +then+ resource will be stopped and restarted. === Advisory Ordering === On the other hand, when +score="0"+ is specified for a constraint, the constraint is considered optional and only has an effect when both resources are stopping and/or starting. Any change in state by the +first+ resource will have no effect on the +then+ resource. .Example of an optional and mandatory ordering constraint +====== [source,XML] ------- ------- +====== Some additional information on ordering constraints can be found in the document http://www.clusterlabs.org/mediawiki/images/d/d6/Ordering_Explained.pdf[Ordering Explained]. == Placing Resources Relative to other Resources == anchor:s-resource-colocation[Resource Colocation] When the location of one resource depends on the location of another one, we call this colocation. There is an important side-effect of creating a colocation constraint between two resources: it affects the order in which resources are assigned to a node. If you think about it, it's somewhat obvious. You can't place A relative to B unless you know where B is. footnote:[ While the human brain is sophisticated enough to read the constraint in any order and choose the correct one depending on the situation, the cluster is not quite so smart. Yet. ] So when you are creating colocation constraints, it is important to consider whether you should colocate A with B or B with A. Another thing to keep in mind is that, assuming A is collocated with B, the cluster will also take into account A's preferences when deciding which node to choose for B. For a detailed look at exactly how this occurs, see the http://www.clusterlabs.org/mediawiki/images/6/61/Colocation_Explained.pdf[Colocation Explained] document. === Options === .Properties of a Collocation Constraint [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |id |A unique name for the constraint. |rsc |The colocation source. If the constraint cannot be satisfied, the cluster may decide not to allow the resource to run at all. |with-rsc |The colocation target. The cluster will decide where to put this resource first and then decide where to put the resource in the +rsc+ field. |score |Positive values indicate the resource should run on the same node. Negative values indicate the resources should not run on the same node. Values of \+/- +INFINITY+ change "should" to "must". |========================================================= === Mandatory Placement === Mandatory placement occurs any time the constraint's score is ++INFINITY+ or +-INFINITY+. In such cases, if the constraint can't be satisfied, then the +rsc+ resource is not permitted to run. For +score=INFINITY+, this includes cases where the +with-rsc+ resource is not active. If you need +resource1+ to always run on the same machine as +resource2+, you would add the following constraint: .An example colocation constraint [source,XML] Remember, because +INFINITY+ was used, if +resource2+ can't run on any of the cluster nodes (for whatever reason) then +resource1+ will not be allowed to run. Alternatively, you may want the opposite... that +resource1+ cannot run on the same machine as +resource2+. In this case use +score="-INFINITY"+ .An example anti-colocation constraint [source,XML] Again, by specifying +-INFINTY+, the constraint is binding. So if the only place left to run is where +resource2+ already is, then +resource1+ may not run anywhere. === Advisory Placement === If mandatory placement is about "must" and "must not", then advisory placement is the "I'd prefer if" alternative. For constraints with scores greater than +-INFINITY+ and less than +INFINITY+, the cluster will try and accommodate your wishes but may ignore them if the alternative is to stop some of the cluster resources. Like in life, where if enough people prefer something it effectively becomes mandatory, advisory colocation constraints can combine with other elements of the configuration to behave as if they were mandatory. .An example advisory-only colocation constraint [source,XML] == Ordering Sets of Resources == anchor:s-resource-sets-ordering[Resource Sets - Start Ordering] A common situation is for an administrator to create a chain of ordered resources, such as: .A chain of ordered resources +====== [source,XML] ------- ------- +====== == Ordered Set == .Visual representation of the four resources' start order for the above constraints image::images/resource-set.png["Ordered set",width="16cm",height="2.5cm",align="center"] To simplify this situation, there is an alternate format for ordering constraints: .A chain of ordered resources expressed as a set +====== [source,XML] ------- ------- +====== [NOTE] Resource sets have the same ordering semantics as groups. .A group resource with the equivalent ordering rules +====== [source,XML] ------- ------- +====== While the set-based format is not less verbose, it is significantly easier to get right and maintain. It can also be expanded to allow ordered sets of (un)ordered resources. In the example below, +rscA+ and +rscB+ can both start in parallel, as can +rscC+ and +rscD+, however +rscC+ and +rscD+ can only start once _both_ +rscA+ _and_ +rscB+ are active. .Ordered sets of unordered resources +====== [source,XML] ------- ------- +====== == Two Sets of Unordered Resources == .Visual representation of the start order for two ordered sets of unordered resources image::images/two-sets.png["Two ordered sets",width="13cm",height="7.5cm",align="center"] Of course either set -- or both sets -- of resources can also be internally ordered (by setting +sequential="true"+) and there is no limit to the number of sets that can be specified. .Advanced use of set ordering - Three ordered sets, two of which are internally unordered +====== [source,XML] ------- ------- +====== == Three Resources Sets == .Visual representation of the start order for the three sets defined above image::images/three-sets.png["Three ordered sets",width="16cm",height="7.5cm",align="center"] == Collocating Sets of Resources == anchor:s-resource-sets-collocation[Resource Sets - Colocation] Another common situation is for an administrator to create a set of collocated resources. Previously this was possible either by defining a resource group (See xref:group-resources[]) which could not always accurately express the design; or by defining each relationship as an individual constraint, causing a constraint explosion as the number of resources and combinations grew. .A chain of collocated resources +====== [source,XML] ------- ------- +====== To make things easier, we allow an alternate form of colocation constraints using +resource_sets+. Just like the expanded version, a resource that can't be active also prevents any resource that must be collocated with it from being active. For example, if +B was+ not able to run, then both +C (+and by inference +D)+ must also remain stopped. .The equivalent colocation chain expressed using +resource_sets+ +====== [source,XML] ------- ------- +====== [NOTE] Resource sets have the same colocation semantics as groups. .A group resource with the equivalent colocation rules [source,XML] ------- ------- This notation can also be used in this context to tell the cluster that a set of resources must all be located with a common peer, but have no dependencies on each other. In this scenario, unlike the previous, +B would+ be allowed to remain active even if +A or+ +C+ (or both) were inactive. .Using colocation sets to specify a common peer. +====== [source,XML] ------- ------- +====== Of course there is no limit to the number and size of the sets used. The only thing that matters is that in order for any member of set N to be active, all the members of set N+1 must also be active (and naturally on the same node); and if a set has +sequential="true"+, then in order for member M to be active, member M+1 must also be active. You can even specify the role in which the members of a set must be in using the set's role attribute. .A colocation chain where the members of the middle set have no inter-dependencies and the last has master status. +====== [source,XML] ------- ------- +====== == Another Three Resources Sets == .Visual representation of a colocation chain where the members of the middle set have no inter-dependencies image::images/three-sets-complex.png["Colocation chain",width="16cm",height="9cm",align="center"] diff --git a/doc/Pacemaker_Explained/en-US/Ch-Multi-site-Clusters.txt b/doc/Pacemaker_Explained/en-US/Ch-Multi-site-Clusters.txt index 4e0cfed0ac..efd2f7a5b2 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Multi-site-Clusters.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Multi-site-Clusters.txt @@ -1,361 +1,361 @@ = Multi-Site Clusters and Tickets = [[Multisite]] == Abstract == Apart from local clusters, Pacemaker also supports multi-site clusters. That means you can have multiple, geographically dispersed sites with a local cluster each. Failover between these clusters can be coordinated by a higher level entity, the so-called `CTR (Cluster Ticket Registry)`. == Challenges for Multi-Site Clusters == Typically, multi-site environments are too far apart to support synchronous communication between the sites and synchronous data replication. That leads to the following challenges: - How to make sure that a cluster site is up and running? - How to make sure that resources are only started once? - How to make sure that quorum can be reached between the different sites and a split brain scenario can be avoided? - How to manage failover between the sites? - How to deal with high latency in case of resources that need to be stopped? In the following sections, learn how to meet these challenges. == Conceptual Overview == Multi-site clusters can be considered as “overlay” clusters where each cluster site corresponds to a cluster node in a traditional cluster. The overlay cluster can be managed by a `CTR (Cluster Ticket Registry)` mechanism. It guarantees that the cluster resources will be highly available across different cluster sites. This is achieved by using so-called `tickets` that are treated as failover domain between cluster sites, in case a site should be down. The following list explains the individual components and mechanisms that were introduced for multi-site clusters in more detail. === Components and Concepts === ==== Ticket ==== "Tickets" are, essentially, cluster-wide attributes. A ticket grants the right to run certain resources on a specific cluster site. Resources can be bound to a certain ticket by `rsc_ticket` dependencies. Only if the ticket is available at a site, the respective resources are started. Vice versa, if the ticket is revoked, the resources depending on that ticket need to be stopped. The ticket thus is similar to a 'site quorum'; i.e., the permission to manage/own resources associated with that site. (One can also think of the current `have-quorum` flag as a special, cluster-wide ticket that is granted in case of node majority.) These tickets can be granted/revoked either manually by administrators (which could be the default for the classic enterprise clusters), or via an automated `CTR` mechanism described further below. A ticket can only be owned by one site at a time. Initially, none of the sites has a ticket. Each ticket must be granted once by the cluster administrator. The presence or absence of tickets for a site is stored in the CIB as a cluster status. With regards to a certain ticket, there are only two states for a site: `true` (the site has the ticket) or `false` (the site does not have the ticket). The absence of a certain ticket (during the initial state of the multi-site cluster) is also reflected by the value `false`. ==== Dead Man Dependency ==== A site can only activate the resources safely if it can be sure that the other site has deactivated them. However after a ticket is revoked, it can take a long time until all resources depending on that ticket are stopped "cleanly", especially in case of cascaded resources. To cut that process short, the concept of a `Dead Man Dependency` was introduced: - If the ticket is revoked from a site, the nodes that are hosting dependent resources are fenced. This considerably speeds up the recovery process of the cluster and makes sure that resources can be migrated more quickly. This can be configured by specifying a `loss-policy="fence"` in `rsc_ticket` constraints. ==== CTR (Cluster Ticket Registry) ==== This is for those scenarios where the tickets management is supposed to be automatic (instead of the administrator revoking the ticket somewhere, waiting for everything to stop, and then granting it on the desired site). A `CTR` is a network daemon that handles granting, revoking, and timing out "tickets". The participating clusters would run the daemons that would connect to each other, exchange information on their connectivity details, and vote on which site gets which ticket(s). A ticket would only be granted to a site once they can be sure that it has been relinquished by the previous owner, which would need to be implemented via a timer in most scenarios. If a site loses connection to its peers, its tickets time out and recovery occurs. After the connection timeout plus the recovery timeout has passed, the other sites are allowed to re-acquire the ticket and start the resources again. This can also be thought of as a "quorum server", except that it is not a single quorum ticket, but several. ==== Configuration Replication ==== As usual, the CIB is synchronized within each cluster, but it is not synchronized across cluster sites of a multi-site cluster. You have to configure the resources that will be highly available across the multi-site cluster for every site accordingly. == Configuring Ticket Dependencies == The `rsc_ticket` constraint lets you specify the resources depending on a certain ticket. Together with the constraint, you can set a `loss-policy` that defines what should happen to the respective resources if the ticket is revoked. The attribute `loss-policy` can have the following values: fence:: Fence the nodes that are running the relevant resources. stop:: Stop the relevant resources. freeze:: Do nothing to the relevant resources. demote:: Demote relevant resources that are running in master mode to slave mode. An example to configure a `rsc_ticket` constraint: [source,XML] ------- ------- This creates a constraint with the ID `rsc1-req-ticketA`. It defines that the resource `rsc1` depends on `ticketA` and that the node running the resource should be fenced in case `ticketA` is revoked. If resource `rsc1` was a multi-state resource that can run in master or slave mode, you may want to configure that only `rsc1's` master mode depends on `ticketA`. With the following configuration, `rsc1` will be demoted to slave mode if `ticketA` is revoked: [source,XML] ------- ------- You can create more `rsc_ticket` constraints to let multiple resources depend on the same ticket. `rsc_ticket` also supports resource sets. So one can easily list all the resources in one `rsc_ticket` constraint. For example: [source,XML] ------- ------- In the example, there are two resource sets for listing the resources with different `roles` in one `rsc_ticket` constraint. There's no dependency between the two resource sets. And there's no dependency among the resources within a resource set. Each of the resources just depends on `ticketA`. Referencing resource templates in `rsc_ticket` constraints, and even referencing them within resource sets, is also supported. If you want other resources to depend on further tickets, create as many constraints as necessary with `rsc_ticket`. == Managing Multi-Site Clusters == === Granting and Revoking Tickets Manually === You can grant tickets to sites or revoke them from sites manually. Though if you want to re-distribute a ticket, you should wait for the dependent resources to cleanly stop at the previous site before you grant the ticket to another desired site. Use the `crm_ticket` command line tool to grant and revoke tickets. To grant a ticket to this site: -[source,Bash] +[source,C] ------- # crm_ticket --ticket ticketA --grant ------- To revoke a ticket from this site: -[source,Bash] +[source,C] ------- # crm_ticket --ticket ticketA --revoke ------- [IMPORTANT] ==== If you are managing tickets manually. Use the `crm_ticket` command with great care as they cannot help verify if the same ticket is already granted elsewhere. ==== === Granting and Revoking Tickets via a Cluster Ticket Registry === ==== Booth ==== Booth is an implementation of `Cluster Ticket Registry` or so-called `Cluster Ticket Manager`. Booth is the instance managing the ticket distribution and thus, the failover process between the sites of a multi-site cluster. Each of the participating clusters and arbitrators runs a service, the boothd. It connects to the booth daemons running at the other sites and exchanges connectivity details. Once a ticket is granted to a site, the booth mechanism will manage the ticket automatically: If the site which holds the ticket is out of service, the booth daemons will vote which of the other sites will get the ticket. To protect against brief connection failures, sites that lose the vote (either explicitly or implicitly by being disconnected from the voting body) need to relinquish the ticket after a time-out. Thus, it is made sure that a ticket will only be re-distributed after it has been relinquished by the previous site. The resources that depend on that ticket will fail over to the new site holding the ticket. The nodes that have run the resources before will be treated according to the `loss-policy` you set within the `rsc_ticket` constraint. Before the booth can manage a certain ticket within the multi-site cluster, you initially need to grant it to a site manually via `booth client` command. After you have initially granted a ticket to a site, the booth mechanism will take over and manage the ticket automatically. [IMPORTANT] ==== The `booth client` command line tool can be used to grant, list, or revoke tickets. The `booth client` commands work on any machine where the booth daemon is running. If you are managing tickets via `Booth`, only use `booth client` for manual intervention instead of `crm_ticket`. That can make sure the same ticket will only be owned by one cluster site at a time. ==== Booth includes an implementation of http://en.wikipedia.org/wiki/Paxos_algorithm['Paxos'] and 'Paxos Lease' algorithm, which guarantees the distributed consensus among different cluster sites. [NOTE] ==== `Arbitrator` Each site runs one booth instance that is responsible for communicating with the other sites. If you have a setup with an even number of sites, you need an additional instance to reach consensus about decisions such as failover of resources across sites. In this case, add one or more arbitrators running at additional sites. Arbitrators are single machines that run a booth instance in a special mode. As all booth instances communicate with each other, arbitrators help to make more reliable decisions about granting or revoking tickets. An arbitrator is especially important for a two-site scenario: For example, if site `A` can no longer communicate with site `B`, there are two possible causes for that: - `A` network failure between `A` and `B`. - Site `B` is down. However, if site `C` (the arbitrator) can still communicate with site `B`, site `B` must still be up and running. ==== ===== Requirements ===== - All clusters that will be part of the multi-site cluster must be based on Pacemaker. - Booth must be installed on all cluster nodes and on all arbitrators that will be part of the multi-site cluster. The most common scenario is probably a multi-site cluster with two sites and a single arbitrator on a third site. However, technically, there are no limitations with regards to the number of sites and the number of arbitrators involved. Nodes belonging to the same cluster site should be synchronized via NTP. However, time synchronization is not required between the individual cluster sites. === General Management of Tickets === Display the information of tickets: -[source,Bash] +[source,C] ------- # crm_ticket --info ------- Or you can monitor them with: -[source,Bash] +[source,C] ------- # crm_mon --tickets ------- Display the rsc_ticket constraints that apply to a ticket: -[source,Bash] +[source,C] ------- # crm_ticket --ticket ticketA --constraints ------- When you want to do maintenance or manual switch-over of a ticket, the ticket could be revoked from the site for any reason, which would trigger the loss-policies. If `loss-policy="fence"`, the dependent resources could not be gracefully stopped/demoted, and even, other unrelated resources could be impacted. The proper way is making the ticket `standby` first with: -[source,Bash] +[source,C] ------- # crm_ticket --ticket ticketA --standby ------- Then the dependent resources will be stopped or demoted gracefully without triggering the loss-policies. If you have finished the maintenance and want to activate the ticket again, you can run: -[source,Bash] +[source,C] ------- # crm_ticket --ticket ticketA --activate ------- == For more information == `Multi-site Clusters` http://doc.opensuse.org/products/draft/SLE-HA/SLE-ha-guide_sd_draft/cha.ha.geo.html `Booth` https://github.com/ClusterLabs/booth diff --git a/doc/Pacemaker_Explained/en-US/Ch-Nodes.txt b/doc/Pacemaker_Explained/en-US/Ch-Nodes.txt index a4e34e3067..3b599521c6 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Nodes.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Nodes.txt @@ -1,157 +1,159 @@ = Cluster Nodes = == Defining a Cluster Node == Each node in the cluster will have an entry in the nodes section containing its UUID, uname, and type. .Example cluster node entry +====== [source,XML] -------- -------- +====== In normal circumstances, the admin should let the cluster populate this information automatically from the communications and membership data. However one can use the `crm_uuid` tool to read an existing UUID or define a value before the cluster starts. == Describing a Cluster Node == anchor:s-node-attributes[Describing a Cluster Node] Beyond the basic definition of a node the administrator can also describe the node's attributes, such as how much RAM, disk, what OS or kernel version it has, perhaps even its physical location. This information can then be used by the cluster when deciding where to place resources. For more information on the use of node attributes, see the section on xref:ch-rules[]. Node attributes can be specified ahead of time or populated later, when the cluster is running, using `crm_attribute`. Below is what the node's definition would look like if the admin ran the command: .The result of using crm_attribute to specify which kernel pcmk-1 is running -[source,XML] +====== +[source,C] ------- # crm_attribute --type nodes --node-uname pcmk-1 --attr-name kernel --attr-value `uname -r` - +------- +[source,XML] +------- ------- - +====== A simpler way to determine the current value of an attribute is to use `crm_attribute` command again: - ` crm_attribute --type nodes --node-uname pcmk-1 --attr-name kernel --get-value` +[source,C] +# crm_attribute --type nodes --node-uname pcmk-1 --attr-name kernel --get-value By specifying --type nodes the admin tells the cluster that this attribute is persistent. There are also transient attributes which are kept in the status section which are "forgotten" whenever the node rejoins the cluster. The cluster uses this area to store a record of how many times a resource has failed on that node but administrators can also read and write to this section by specifying --type status. == Adding a New Cluster Node == === Corosync === Adding a new node is as simple as installing Corosync and Pacemaker, and copying _/etc/corosync/corosync.conf_ and _/etc/ais/authkey_ (if it exists) from an existing node. You may need to modify the +mcastaddr+ option to match the new node's IP address. If a log message containing "Invalid digest" appears from Corosync, the keys are not consistent between the machines. === Heartbeat === Provided you specified +autojoin any+ in _ha.cf_, adding a new node is as simple as installing heartbeat and copying _ha.cf_ and _authkeys_ from an existing node. If you don't want to use +autojoin+, then after setting up _ha.cf_ and _authkeys_, you must use the `hb_addnode` command before starting the new node. == Removing a Cluster Node == === Corosync === Because the messaging and membership layers are the authoritative source for cluster nodes, deleting them from the CIB is not a reliable solution. First one must arrange for heartbeat to forget about the node (_pcmk-1_ in the example below). On the host to be removed: . Find and record the node's Corosync id: `crm_node -i` . Stop the cluster: `/etc/init.d/corosync stop` Next, from one of the remaining active cluster nodes: . Tell the cluster to forget about the removed host: + -[source,Bash] -crm_node -R $COROSYNC_ID +[source,C] +# crm_node -R $COROSYNC_ID + . Only now is it safe to delete the node from the CIB with: + -[source,Bash] ------ -cibadmin --delete --obj_type nodes --crm_xml '' -cibadmin --delete --obj_type status --crm_xml '' ------ +[source,C] +# cibadmin --delete --obj_type nodes --crm_xml '' +# cibadmin --delete --obj_type status --crm_xml '' === Heartbeat === Because the messaging and membership layers are the authoritative source for cluster nodes, deleting them from the CIB is not a reliable solution. First one must arrange for heartbeat to forget about the node (pcmk-1 in the example below). To do this, shut down heartbeat on the node and then, from one of the remaining active cluster nodes, run: -[source,Bash] -hb_delnode pcmk-1 +[source,C] +# hb_delnode pcmk-1 Only then is it safe to delete the node from the CIB with: -[source,Bash] +[source,C] ----- -cibadmin --delete --obj_type nodes --crm_xml '' -cibadmin --delete --obj_type status --crm_xml '' +# cibadmin --delete --obj_type nodes --crm_xml '' +# cibadmin --delete --obj_type status --crm_xml '' ----- == Replacing a Cluster Node == === Corosync === The five-step guide to replacing an existing cluster node: . Make sure the old node is completely stopped . Give the new machine the same hostname and IP address as the old one . Install the cluster software :-) . Copy _/etc/corosync/corosync.conf_ and _/etc/ais/authkey_ (if it exists) to the new node . Start the new cluster node If a log message containing "Invalid digest" appears from Corosync, the keys are not consistent between the machines. === Heartbeat === The seven-step guide to replacing an existing cluster node: . Make sure the old node is completely stopped . Give the new machine the same hostname as the old one . Go to an active cluster node and look up the UUID for the old node in _/var/lib/heartbeat/hostcache_ . Install the cluster software . Copy _ha.cf_ and _authkeys_ to the new node . On the new node, populate it's UUID using `crm_uuid -w` and the UUID from step 2 . Start the new cluster node diff --git a/doc/Pacemaker_Explained/en-US/Ch-Options.txt b/doc/Pacemaker_Explained/en-US/Ch-Options.txt index 180f4c906e..d40a09b812 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Options.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Options.txt @@ -1,278 +1,285 @@ = Cluster Options = == Special Options == indexterm:[Special Cluster Options] indexterm:[Cluster Options,Special Options] The reason for these fields to be placed at the top level instead of with the rest of cluster options is simply a matter of parsing. These options are used by the configuration database which is, by design, mostly ignorant of the content it holds. So the decision was made to place them in an easy to find location. == Configuration Version == indexterm:[Configuration Version, Cluster Option] indexterm:[Cluster Options,Configuration Version] When a node joins the cluster, the cluster will perform a check to see who has the best configuration based on the fields below. It then asks the node with the highest (+admin_epoch+, +epoch+, +num_updates+) tuple to replace the configuration on all the nodes - which makes setting them, and setting them correctly, very important. .Configuration Version Properties [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description | admin_epoch | indexterm:[admin_epoch Cluster Option] indexterm:[Cluster Options,admin_epoch] Never modified by the cluster. Use this to make the configurations on any inactive nodes obsolete. _Never set this value to zero_, in such cases the cluster cannot tell the difference between your configuration and the "empty" one used when nothing is found on disk. | epoch | indexterm:[epoch Cluster Option] indexterm:[Cluster Options,epoch] Incremented every time the configuration is updated (usually by the admin) | num_updates | indexterm:[num_updates Cluster Option] indexterm:[Cluster Options,num_updates] Incremented every time the configuration or status is updated (usually by the cluster) |========================================================= == Other Fields == .Properties Controlling Validation [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description | validate-with | indexterm:[validate-with Cluster Option] indexterm:[Cluster Options,validate-with] Determines the type of validation being done on the configuration. If set to "none", the cluster will not verify that updates conform to the DTD (nor reject ones that don't). This option can be useful when operating a mixed version cluster during an upgrade. |========================================================= == Fields Maintained by the Cluster == .Properties Maintained by the Cluster [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |cib-last-written | indexterm:[cib-last-written Cluster Fields] indexterm:[Cluster Fields,cib-last-written] Indicates when the configuration was last written to disk. Informational purposes only. |dc-uuid | indexterm:[dc-uuid Cluster Fields] indexterm:[Cluster Fields,dc-uuid] Indicates which cluster node is the current leader. Used by the cluster when placing resources and determining the order of some events. |have-quorum | indexterm:[have-quorum Cluster Fields] indexterm:[Cluster Fields,have-quorum] Indicates if the cluster has quorum. If false, this may mean that the cluster cannot start resources or fence other nodes. See +no-quorum-policy+ below. |========================================================= Note that although these fields can be written to by the admin, in most cases the cluster will overwrite any values specified by the admin with the "correct" ones. To change the +admin_epoch+, for example, one would use: `cibadmin --modify --crm_xml ‘<cib admin_epoch="42"/>'` A complete set of fields will look something like this: .An example of the fields set for a cib object +====== [source,XML] ------- ------- +====== == Cluster Options == Cluster options, as you might expect, control how the cluster behaves when confronted with certain situations. They are grouped into sets and, in advanced configurations, there may be more than one. footnote:[This will be described later in the section on <> where we will show how to have the cluster use different sets of options during working hours (when downtime is usually to be avoided at all costs) than it does during the weekends (when resources can be moved to the their preferred hosts without bothering end users)] For now we will describe the simple case where each option is present at most once. == Available Cluster Options == .Cluster Options [width="95%",cols="5m,2m,13",options="header",align="center"] |========================================================= |Option |Default |Description | batch-limit | 30 | indexterm:[batch-limit Cluster Options] indexterm:[Cluster Options,batch-limit] The number of jobs that the TE is allowed to execute in parallel. The "correct" value will depend on the speed and load of your network and cluster nodes. | migration-limit | -1 (unlimited) | indexterm:[migration-limit Cluster Options] indexterm:[Cluster Options,migration-limit] The number of migration jobs that the TE is allowed to execute in parallel on a node. | no-quorum-policy | stop | indexterm:[no-quorum-policy Cluster Options] indexterm:[Cluster Options,no-quorum-policy] What to do when the cluster does not have quorum. Allowed values: * ignore - continue all resource management * freeze - continue resource management, but don't recover resources from nodes not in the affected partition * stop - stop all resources in the affected cluster partition * suicide - fence all nodes in the affected cluster partition | symmetric-cluster | TRUE | indexterm:[symmetric-cluster Cluster Options] indexterm:[Cluster Options,symmetric-cluster] Can all resources run on any node by default? | stonith-enabled | TRUE | indexterm:[stonith-enabled Cluster Options] indexterm:[Cluster Options,stonith-enabled] Should failed nodes and nodes with resources that can't be stopped be shot? If you value your data, set up a STONITH device and enable this. If true, or unset, the cluster will refuse to start resources unless one or more STONITH resources have been configured also. | stonith-action | reboot | indexterm:[stonith-action Cluster Options] indexterm:[Cluster Options,stonith-action] Action to send to STONITH device. Allowed values: reboot, off. The value 'poweroff' is also allowed, but is only used for legacy devices. | cluster-delay | 60s | indexterm:[cluster-delay Cluster Options] indexterm:[Cluster Options,cluster-delay] Round trip delay over the network (excluding action execution). The "correct" value will depend on the speed and load of your network and cluster nodes. | stop-orphan-resources | TRUE | indexterm:[stop-orphan-resources Cluster Options] indexterm:[Cluster Options,stop-orphan-resources] Should deleted resources be stopped? | stop-orphan-actions | TRUE | indexterm:[stop-orphan-actions Cluster Options] indexterm:[Cluster Options,stop-orphan-actions] Should deleted actions be cancelled? | start-failure-is-fatal | TRUE | indexterm:[start-failure-is-fatal Cluster Options] indexterm:[Cluster Options,start-failure-is-fatal] When set to FALSE, the cluster will instead use the resource's +failcount+ and value for +resource-failure-stickiness+. | pe-error-series-max | -1 (all) | indexterm:[pe-error-series-max Cluster Options] indexterm:[Cluster Options,pe-error-series-max] The number of PE inputs resulting in ERRORs to save. Used when reporting problems. | pe-warn-series-max | -1 (all) | indexterm:[pe-warn-series-max Cluster Options] indexterm:[Cluster Options,pe-warn-series-max] The number of PE inputs resulting in WARNINGs to save. Used when reporting problems. | pe-input-series-max | -1 (all) | indexterm:[pe-input-series-max Cluster Options] indexterm:[Cluster Options,pe-input-series-max] The number of "normal" PE inputs to save. Used when reporting problems. |========================================================= You can always obtain an up-to-date list of cluster options, including their default values, by running the `pengine metadata` command. == Querying and Setting Cluster Options == indexterm:[Querying Cluster Options] indexterm:[Setting Cluster Options] indexterm:[Cluster Options,Querying] indexterm:[Cluster Options,Setting] Cluster options can be queried and modified using the `crm_attribute` tool. To get the current value of +cluster-delay+, simply use: -`crm_attribute --attr-name cluster-delay --get-value` +[source,C] +# crm_attribute --attr-name cluster-delay --get-value which is more simply written as -`crm_attribute --get-value -n cluster-delay` +[source,C] +# crm_attribute --get-value -n cluster-delay If a value is found, you'll see a result like this: -======= -` # crm_attribute --get-value -n cluster-delay` +[source,C] +# crm_attribute --get-value -n cluster-delay name=cluster-delay value=60s -======== However, if no value is found, the tool will display an error: -======= -`# crm_attribute --get-value -n clusta-deway` - name=clusta-deway value=(null) - Error performing operation: The object/attribute does not exist -======== +[source,C] +# crm_attribute --get-value -n clusta-deway` +name=clusta-deway value=(null) +Error performing operation: The object/attribute does not exist To use a different value, eg. +30+, simply run: -`crm_attribute --attr-name cluster-delay --attr-value 30s` +[source,C] +# crm_attribute --attr-name cluster-delay --attr-value 30s To go back to the cluster's default value you can delete the value, for example with this command: -`crm_attribute --attr-name cluster-delay --delete-attr` +[source,C] +# crm_attribute --attr-name cluster-delay --delete-attr == When Options are Listed More Than Once == If you ever see something like the following, it means that the option you're modifying is present more than once. .Deleting an option that is listed twice ======= -`# crm_attribute --attr-name batch-limit --delete-attr` - - Multiple attributes match name=batch-limit in crm_config: - Value: 50 (set=cib-bootstrap-options, id=cib-bootstrap-options-batch-limit) - Value: 100 (set=custom, id=custom-batch-limit) - Please choose from one of the matches above and supply the 'id' with --attr-id +[source,C] +------ +# crm_attribute --attr-name batch-limit --delete-attr + +Multiple attributes match name=batch-limit in crm_config: +Value: 50 (set=cib-bootstrap-options, id=cib-bootstrap-options-batch-limit) +Value: 100 (set=custom, id=custom-batch-limit) +Please choose from one of the matches above and supply the 'id' with --attr-id +------- ======= In such cases follow the on-screen instructions to perform the requested action. To determine which value is currently being used by the cluster, please refer to the section on <>. diff --git a/doc/Pacemaker_Explained/en-US/Ch-Resource-Templates.txt b/doc/Pacemaker_Explained/en-US/Ch-Resource-Templates.txt index ccc99d7719..5c34ae7ef7 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Resource-Templates.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Resource-Templates.txt @@ -1,222 +1,216 @@ = Resource Templates = == Abstract == If you want to create lots of resources with similar configurations, defining a resource template simplifies the task. Once defined, it can be referenced in primitives or in certain types of constraints. == Configuring Resources with Templates == The primitives referencing the template will inherit all meta attributes, instance attributes, utilization attributes and operations defined in the template. And you can define specific attributes and operations for any of the primitives. If any of these are defined in both the template and the primitive, the values defined in the primitive will take precedence over the ones defined in the template. Hence, resource templates help to reduce the amount of configuration work. If any changes are needed, they can be done to the template definition and will take effect globally in all resource definitions referencing that template. Resource templates have a similar syntax like primitives. For example: [source,XML] ---- - + ---- Once you defined the new resource template, you can use it in primitives: [source,XML] ---- - - - - - - + + + + + + ---- The new primitive `vm1` is going to inherit everything from the `vm-template`. For example, the equivalent of the above two would be: [source,XML] ---- ---- If you want to overwrite some attributes or operations, add them to the particular primitive's definition. For instance, the following new primitive `vm2` has special attribute values. Its `monitor` operation has a longer `timeout` and `interval`, and the primitive has an additional `stop` operation. [source,XML] ---- - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + ---- The following command shows the resulting definition of a resource: -[source,Bash] ----- +[source,C] # crm_resource --query-xml --resource vm2 ----- The following command shows its raw definition in cib: -[source,Bash] ----- +[source,C] # crm_resource --query-xml-raw --resource vm2 ----- == Referencing Templates in Constraints == A resource template can be referenced in the following types of constraints: - `order` constraints - `colocation` constraints, - `rsc_ticket` constraints (for multi-site clusters). Resource templates referenced in constraints stand for all primitives which are derived from that template. This means, the constraint applies to all primitive resources referencing the resource template. Referencing resource templates in constraints is an alternative to resource sets and can simplify the cluster configuration considerably. For example: [source,XML] ----- ----- is the equivalent of the following constraint configuration: [source,XML] ---- - - - - - - - - - + + + + + + + + + ---- [NOTE] ====== In a colocation constraint, only one template may be referenced from either `rsc` or `with-rsc`, and the other reference must be a regular resource. ====== Resource templates can also be referenced in resource sets. For example: [source,XML] ---- - - - - - - - + + + + + + + ---- is the equivalent of the following constraint configuration: [source,XML] ---- - - - - - - - - + + + + + + + + ---- If the resources referencing the template can run in parallel: [source,XML] ---- - - - - - - - - - - - + + + + + + + + + + + ---- is the equivalent of the following constraint configuration: [source,XML] ---- - - - - - - - - - - - - + + + + + + + + + + + + ---- diff --git a/doc/Pacemaker_Explained/en-US/Ch-Resources.txt b/doc/Pacemaker_Explained/en-US/Ch-Resources.txt index a264c8e8c4..9cf224d623 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Resources.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Resources.txt @@ -1,591 +1,607 @@ = Cluster Resources = == What is a Cluster Resource == indexterm:[Resource,Description] The role of a resource agent is to abstract the service it provides and present a consistent view to the cluster, which allows the cluster to be agnostic about the resources it manages. The cluster doesn't need to understand how the resource works because it relies on the resource agent to do the right thing when given a +start+, +stop+ or +monitor+ command. For this reason it is crucial that resource agents are well tested. Typically resource agents come in the form of shell scripts, however they can be written using any technology (such as C, Python or Perl) that the author is comfortable with. == Supported Resource Classes == indexterm:[Resource,Classes] anchor:s-resource-supported[Supported Resource Classes] There are three basic classes of agents supported by Pacemaker. In order of encouraged usage they are: === Open Cluster Framework === indexterm:[Resource,OCF] indexterm:[OCF,Resources] indexterm:[Open Cluster Framework,Resources] The OCF standard footnote:[ http://www.opencf.org/cgi-bin/viewcvs.cgi/specs/ra/resource-agent-api.txt?rev=HEAD - at least as it relates to resource agents. ] footnote:[ The Pacemaker implementation has been somewhat extended from the OCF Specs, but none of those changes are incompatible with the original OCF specification. ] is basically an extension of the Linux Standard Base conventions for init scripts to: * support parameters, * make them self describing and * extensible OCF specs have strict definitions of the exit codes that actions must return. footnote:[ Included with the cluster is the ocf-tester script, which can be useful in this regard. ] The cluster follows these specifications exactly, and giving the wrong exit code will cause the cluster to behave in ways you will likely find puzzling and annoying. In particular, the cluster needs to distinguish a completely stopped resource from one which is in some erroneous and indeterminate state. Parameters are passed to the script as environment variables, with the special prefix +OCF_RESKEY_+. So, a parameter which the user thinks of as ip it will be passed to the script as +OCF_RESKEY_ip+. The number and purpose of the parameters is completely arbitrary, however your script should advertise any that it supports using the +meta-data+ command. The OCF class is the most preferred one as it is an industry standard, highly flexible (allowing parameters to be passed to agents in a non-positional manner) and self-describing. For more information, see the http://www.linux-ha.org/wiki/OCF_Resource_Agents[reference] and xref:ap-ocf[]. === Linux Standard Base === indexterm:[Resource,LSB] indexterm:[LSB,Resources] indexterm:[Linus Standard Base,Resources] LSB resource agents are those found in '/etc/init.d'. Generally they are provided by the OS/distribution and, in order to be used with the cluster, they must conform to the LSB Spec. footnote:[ See http://refspecs.linux-foundation.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html for the LSB Spec (as it relates to init scripts). ] Many distributions claim LSB compliance but ship with broken init scripts. To see if your init script is LSB-compatible, see the FAQ entry xref:ap-lsb[]. The most common problems are: * Not implementing the status operation at all * Not observing the correct exit status codes for start/stop/status actions * Starting a started resource returns an error (this violates the LSB spec) * Stopping a stopped resource returns an error (this violates the LSB spec) === Legacy Heartbeat === indexterm:[Resource,Heartbeat (legacy)] indexterm:[Heartbeat,Legacy Resources] Version 1 of Heartbeat came with its own style of resource agents and it is highly likely that many people have written their own agents based on its conventions. To enable administrators to continue to use these agents, they are supported by the new cluster manager footnote:[ See http://wiki.linux-ha.org/HeartbeatResourceAgent for more information ] === STONITH === indexterm:[Resource,STONITH] indexterm:[STONITH,Resources] There is also an additional class, STONITH, which is used exclusively for fencing related resources. This is discussed later in xref:ch-stonith[]. == Properties == anchor:primitive-resource[primitive] These values tell the cluster which script to use for the resource, where to find that script and what standards it conforms to. .Properties of a Primitive Resource [width="95%",cols="1m,6<",options="header",align="center"] |========================================================= |Field |Description |id indexterm:[id] |Your name for the resource |class indexterm:[class,Resource Field] indexterm:[Resource,Field,class] |The standard the script conforms to. Allowed values: +heartbeat+, +lsb+, +ocf+, +stonith+ |type indexterm:[type,Resource Field] indexterm:[Resource,Field,type] |The name of the Resource Agent you wish to use. Eg. _IPaddr_ or _Filesystem_ |provider indexterm:[provider,Resource Field] indexterm:[Resource,Field,provider] |The OCF spec allows multiple vendors to supply the same ResourceAgent. To use the OCF resource agents supplied with Heartbeat, you should specify +heartbeat+ here. |========================================================= Resource definitions can be queried with the `crm_resource` tool. For example -[source,Bash] -crm_resource --resource Email --query-xml +[source,C] +# crm_resource --resource Email --query-xml might produce: .An example LSB resource +===== [source,XML] +===== [NOTE] One of the main drawbacks to LSB resources is that they do not allow any parameters! -Example for an OCF resource: - .An example OCF resource +===== [source,XML] ------- ------- +===== Or, finally for the equivalent legacy Heartbeat resource: .An example Heartbeat resource +===== [source,XML] ------- ------- +===== [NOTE] ====== Heartbeat resources take only ordered and unnamed parameters. The supplied name therefore indicates the order in which they are passed to the script. Only single digit values are allowed. ====== == Resource Options == anchor:s-resource-options[Resource Options] Options are used by the cluster to decide how your resource should behave and can be easily set using the `--meta` option of the `crm_resource` command. .Options for a Primitive Resource [width="95%",cols="1m,1,4<",options="header",align="center"] |========================================================= |Field |Default |Description |priority |+0+ |If not all resources can be active, the cluster will stop lower priority resources in order to keep higher priority ones active. indexterm:[priority,Resource Option] indexterm:[Resource,Option,priority] |target-role |+Started+ |What state should the cluster attempt to keep this resource in? Allowed values: * 'Stopped' - Force the resource to be stopped * 'Started' - Allow the resource to be started (In the case of xref:s-resource-multistate[] resources, they will not promoted to master) * 'Master' - Allow the resource to be started and, if appropriate, promoted indexterm:[target-role,Resource Option] indexterm:[Resource,Option,target-role] |is-managed |+TRUE+ |Is the cluster allowed to start and stop the resource? Allowed values: +true+, +false+ indexterm:[is-managed,Resource Option] indexterm:[Resource,Option,is-managed] |resource-stickiness |Inherited |How much does the resource prefer to stay where it is? Defaults to the value of +resource-stickiness+ in the +rsc_defaults+ section indexterm:[resource-stickiness,Resource Option] indexterm:[Resource,Option,resource-stickiness] |migration-threshold |+INFINITY+ (disabled) |How many failures may occur for this resource on a node, before this node is marked ineligible to host this resource. indexterm:[migration-threshold,Resource Option] indexterm:[Resource,Option,migration-threshold] |failure-timeout |+0+ (disabled) |How many seconds to wait before acting as if the failure had not occurred, and potentially allowing the resource back to the node on which it failed. indexterm:[failure-timeout,Resource Option] indexterm:[Resource,Option,failure-timeout] |multiple-active |+stop_start+ |What should the cluster do if it ever finds the resource active on more than one node. Allowed values: * 'block' - mark the resource as unmanaged * 'stop_only' - stop all active instances and leave them that way * 'stop_start' - stop all active instances and start the resource in one location only indexterm:[multiple-active,Resource Option] indexterm:[Resource,Option,multiple-active] |========================================================= If you performed the following commands on the previous LSB Email resource -[source,Bash] +[source,C] ------- -crm_resource --meta --resource Email --set-parameter priority --property-value 100 -crm_resource --meta --resource Email --set-parameter multiple-active --property-value block +# crm_resource --meta --resource Email --set-parameter priority --property-value 100 +# crm_resource --meta --resource Email --set-parameter multiple-active --property-value block ------- the resulting resource definition would be .An LSB resource with cluster options +===== [source,XML] ------- ------- +===== == Setting Global Defaults for Resource Options == anchor:s-resource-defaults[Resource Defaults] To set a default value for a resource option, simply add it to the +rsc_defaults+ section with `crm_attribute`. Thus, -[source,Bash] -crm_attribute --type rsc_defaults --attr-name is-managed --attr-value false +[source,C] +# crm_attribute --type rsc_defaults --attr-name is-managed --attr-value false would prevent the cluster from starting or stopping any of the resources in the configuration (unless of course the individual resources were specifically enabled and had +is-managed+ set to +true+). == Instance Attributes == The scripts of some resource classes (LSB not being one of them) can be given parameters which determine how they behave and which instance of a service they control. If your resource agent supports parameters, you can add them with the `crm_resource` command. For instance -[source,Bash] -crm_resource --resource Public-IP --set-parameter ip --property-value 1.2.3.4 +[source,C] +# crm_resource --resource Public-IP --set-parameter ip --property-value 1.2.3.4 would create an entry in the resource like this: .An example OCF resource with instance attributes +===== [source,XML] ------- ------- +===== For an OCF resource, the result would be an environment variable called +OCF_RESKEY_ip+ with a value of +1.2.3.4+. The list of instance attributes supported by an OCF script can be found by calling the resource script with the `meta-data` command. The output contains an XML description of all the supported attributes, their purpose and default values. .Displaying the metadata for the Dummy resource agent template -[source,XML] +===== +[source,C] ------- # export OCF_ROOT=/usr/lib/ocf # $OCF_ROOT/resource.d/pacemaker/Dummy meta-data - +------- +[source,XML] +------- 1.0 This is a Dummy Resource Agent. It does absolutely nothing except keep track of whether its running or not. Its purpose in life is for testing and to serve as a template for RA writers. Dummy resource agent Location to store the resource state in. State file Dummy attribute that can be changed to cause a reload Dummy attribute that can be changed to cause a reload ------- +===== == Resource Operations == === Monitoring Resources for Failure === By default, the cluster will not ensure your resources are still healthy. To instruct the cluster to do this, you need to add a +monitor+ operation to the resource's definition. .An OCF resource with a recurring health check +===== [source,XML] ------- ------- +===== .Properties of an Operation [width="95%",cols="1m,6<",options="header",align="center"] |========================================================= |Field |Description |id |Your name for the action. Must be unique. |name |The action to perform. Common values: +monitor+, +start+, +stop+ |interval |How frequently (in seconds) to perform the operation. Default value: +0+, meaning never. |timeout |How long to wait before declaring the action has failed. |requires |What conditions need to be satisfied before this action occurs. Allowed values: * 'nothing' - The cluster may start this resource at any time * 'quorum' - The cluster can only start this resource if a majority of the configured nodes are active * 'fencing' - The cluster can only start this resource if a majority of the configured nodes are active _and_ any failed or unknown nodes have been powered off. STONITH resources default to +nothing+, and all others default to +fencing+ if STONITH is enabled and +quorum+ otherwise. |on-fail |The action to take if this action ever fails. Allowed values: * 'ignore' - Pretend the resource did not fail * 'block' - Don't perform any further operations on the resource * 'stop' - Stop the resource and do not start it elsewhere * 'restart' - Stop the resource and start it again (possibly on a different node) * 'fence' - STONITH the node on which the resource failed * 'standby' - Move _all_ resources away from the node on which the resource failed The default for the +stop+ operation is +fence+ when STONITH is enabled and +block+ otherwise. All other operations default to +stop+. |enabled |If +false+, the operation is treated as if it does not exist. Allowed values: +true+, +false+ |========================================================= === Setting Global Defaults for Operations === anchor:s-operation-defaults[Operation Defaults] To set a default value for a operation option, simply add it to the +op_defaults+ section with `crm_attribute`. Thus, -[source,Bash] -crm_attribute --type op_defaults --attr-name timeout --attr-value 20s - +[source,C] +# crm_attribute --type op_defaults --attr-name timeout --attr-value 20s would default each operation's +timeout+ to 20 seconds. If an operation's definition also includes a value for +timeout+, then that value would be used instead (for that operation only). ==== When Resources Take a Long Time to Start/Stop ==== There are a number of implicit operations that the cluster will always perform - +start+, +stop+ and a non-recurring +monitor+ operation (used at startup to check the resource isn't already active). If one of these is taking too long, then you can create an entry for them and simply specify a new value. .An OCF resource with custom timeouts for its implicit actions +===== [source,XML] ------- ------- +===== ==== Multiple Monitor Operations ==== Provided no two operations (for a single resource) have the same name and interval you can have as many monitor operations as you like. In this way you can do a superficial health check every minute and progressively more intense ones at higher intervals. To tell the resource agent what kind of check to perform, you need to provide each monitor with a different value for a common parameter. The OCF standard creates a special parameter called +OCF_CHECK_LEVEL+ for this purpose and dictates that it is _"made available to the resource agent without the normal +OCF_RESKEY+ prefix"_. Whatever name you choose, you can specify it by adding an +instance_attributes+ block to the op tag. Note that it is up to each resource agent to look for the parameter and decide how to use it. .An OCF resource with two recurring health checks, performing different levels of checks - specified via +OCF_CHECK_LEVEL+. +===== [source,XML] ------- ------- +===== ==== Disabling a Monitor Operation ==== The easiest way to stop a recurring monitor is to just delete it. However, there can be times when you only want to disable it temporarily. In such cases, simply add +enabled="false"+ to the operation's definition. .Example of an OCF resource with a disabled health check +===== [source,XML] ------- ------- +===== This can be achieved from the command-line by executing -[source,Bash] -cibadmin -M -X ‘' +[source,C] +# cibadmin -M -X '' Once you've done whatever you needed to do, you can then re-enable it with - -[source,Bash] -cibadmin -M -X ‘' diff --git a/doc/Pacemaker_Explained/en-US/Ch-Rules.txt b/doc/Pacemaker_Explained/en-US/Ch-Rules.txt index e8521178f3..e272d14b7b 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Rules.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Rules.txt @@ -1,512 +1,546 @@ = Rules = anchor:ch-rules[Rules] Rules can be used to make your configuration more dynamic. One common example is to set one value for +resource-stickiness+ during working hours, to prevent resources from being moved back to their most preferred location, and another on weekends when no-one is around to notice an outage. Another use of rules might be to assign machines to different processing groups (using a node attribute) based on time and to then use that attribute when creating location constraints. Each rule can contain a number of expressions, date-expressions and even other rules. The results of the expressions are combined based on the rule's +boolean-op+ field to determine if the rule ultimately evaluates to +true+ or +false+. What happens next depends on the context in which the rule is being used. .Properties of a Rule [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |role indexterm:[role Rule Property] indexterm:[Rule,Properties,role] |Limits the rule to apply only when the resource is in that role. Allowed values: _Started_, +Slave,+ and +Master+. NOTE: A rule with +role="Master"+ can not determine the initial location of a clone instance. It will only affect which of the active instances will be promoted. |score indexterm:[score,Rule Property] indexterm:[Rule,Properties,score] |The score to apply if the rule evaluates to +true+. Limited to use in rules that are part of location constraints. |score-attribute indexterm:[score-attribute Rule Property] indexterm:[Rule,Properties,score-attribute] |The node attribute to look up and use as a score if the rule evaluates to +true+. Limited to use in rules that are part of location constraints. |boolean-op indexterm:[boolean-op Rule Property] indexterm:[Rule,Properties,boolean-op] |How to combine the result of multiple expression objects. Allowed values: _and_ and +or+. |========================================================= == Node Attribute Expressions == indexterm:[Node,Attribute Expressions] Expression objects are used to control a resource based on the attributes defined by a node or nodes. In addition to any attributes added by the administrator, each node has a built-in node attribute called +#uname+ that can also be used. .Properties of an Expression [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |value indexterm:[value Expression Property] indexterm:[Expression Properties,value] |User supplied value for comparison |attribute indexterm:[attribute Expression Property] indexterm:[Expression Properties,attribute] |The node attribute to test |type indexterm:[type,Expression Property] indexterm:[Expression Properties,type] |Determines how the value(s) should be tested. Allowed values: _string_, +integer+, +version+ |operation indexterm:[operation Expression Property] indexterm:[Expression Properties,operation] |The comparison to perform. Allowed values: * +lt+ - True if the node attribute's value is less than +value+ * +gt+ - True if the node attribute's value is greater than +value+ * +lte+ - True if the node attribute's value is less than or equal to +value+ * +gte+ - True if the node attribute's value is greater than or equal to +value+ * +eq+ - True if the node attribute's value is equal to +value+ * +ne+ - True if the node attribute's value is not equal to +value+ * +defined+ - True if the node has the named attribute * +not_defined+ - True if the node does not have the named attribute |========================================================= == Time/Date Based Expressions == indexterm:[Time Based Expressions] indexterm:[Expression,Time/Date Based] As the name suggests, +date_expressions+ are used to control a resource or cluster option based on the current date/time. They can contain an optional +date_spec+ and/or +duration+ object depending on the context. .Properties of a Date Expression [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |start |A date/time conforming to the ISO8601 specification. |end |A date/time conforming to the ISO8601 specification. Can be inferred by supplying a value for +start+ and a +duration+. |operation |Compares the current date/time with the start and/or end date, depending on the context. Allowed values: * +gt+ - True if the current date/time is after +start+ * +lt+ - True if the current date/time is before +end+ * +in-range+ - True if the current date/time is after +start+ and before +end+ * +date-spec+ - performs a cron-like comparison to the current date/time |========================================================= [NOTE] ====== Because the comparisons (except for +date_spec+) include the time, the +eq+, +neq+, +gte+ and +lte+ operators have not been implemented. ====== === Date Specifications === indexterm:[Date Specifications] +date_spec+ objects are used to create cron-like expressions relating to time. Each field can contain a single number or a single range. Instead of defaulting to zero, any field not supplied is ignored. For example, +monthdays="1"+ matches the first day of every month and +hours="09-17"+ matches the hours between 9am and 5pm (inclusive). However, at this time one cannot specify +weekdays="1,2"+ or +weekdays="1-2,5-6"+ since they contain multiple ranges. Depending on demand, this may be implemented in a future release. .Properties of a Date Spec [width="95%",cols="1m,5<",options="header",align="center"] |========================================================= |Field |Description |id indexterm:[id,Date Spec Property] indexterm:[Date Spec Properties,id] |A unique name for the date |hours indexterm:[hours Date Spec Property] indexterm:[Date Spec Properties,hours] |Allowed values: 0-23 |monthdays indexterm:[monthdays Date Spec Property] indexterm:[Date Spec Properties,monthdays] |Allowed values: 0-31 (depending on month and year) |weekdays indexterm:[weekdays Date Spec Property] indexterm:[Date Spec Properties,weekdays] |Allowed values: 1-7 (1=Monday, 7=Sunday) |yeardays indexterm:[yeardays Date Spec Property] indexterm:[Date Spec Properties,yeardays] |Allowed values: 1-366 (depending on the year) |months indexterm:[months Date Spec Property] indexterm:[Date Spec Properties,months] |Allowed values: 1-12 |weeks indexterm:[weeks Date Spec Property] indexterm:[Date Spec Properties,weeks] |Allowed values: 1-53 (depending on weekyear) |years indexterm:[years Date Spec Property] indexterm:[Date Spec Properties,years] |Year according the Gregorian calendar |weekyears indexterm:[weekyears Date Spec Property] indexterm:[Date Spec Properties,weekyears] |May differ from Gregorian years; Eg. +2005-001 Ordinal+ is also +2005-01-01 Gregorian+ is also +2004-W53-6 Weekly+ |moon indexterm:[moon Date Spec Property] indexterm:[Date Spec Properties,moon] |Allowed values: 0-7 (0 is new, 4 is full moon). Seriously, you can use this. This was implemented to demonstrate the ease with which new comparisons could be added. |========================================================= === Durations === indexterm:[Durations Expressions] indexterm:[Expressions,Durations] Durations are used to calculate a value for +end+ when one is not supplied to in_range operations. They contain the same fields as +date_spec+ objects but without the limitations (ie. you can have a duration of 19 months). Like +date_specs+, any field not supplied is ignored. == Sample Time Based Expressions == A small sample of how time based expressions can be used. //// -These should have source,XML directives -But then the title doesn't appear. -WTF? +On older versions of asciidoc, the [source] directive makes the title dissappear //// .True if now is any time in the year 2005 +==== +[source,XML] ---- ---- +==== .Equivalent expression +==== +[source,XML] ---- ---- +==== .9am-5pm, Mon-Friday +==== +[source,XML] ------- ------- +==== Please note that the +16+ matches up to +16:59:59+, as the numeric value (hour) still matches! .9am-6pm, Mon-Friday, or all day saturday +==== +[source,XML] ------- ------- +==== .9am-5pm or 9pm-12pm, Mon-Friday +==== +[source,XML] ------- ------- +==== .Mondays in March 2005 +==== +[source,XML] ------- ------- +==== [NOTE] ====== Because no time is specified, 00:00:00 is implied. This means that the range includes all of 2005-03-01 but none of 2005-04-01. You may wish to write +end="2005-03-31T23:59:59"+ to avoid confusion. ====== .A full moon on Friday the 13th +===== +[source,XML] ------- ------- +===== == Using Rules to Determine Resource Location == indexterm:[Rule,Determine Resource Location] indexterm:[Resource,Location, Determine by Rules] If the constraint's outer-most rule evaluates to +false+, the cluster treats the constraint as if it was not there. When the rule evaluates to +true+, the node's preference for running the resource is updated with the score associated with the rule. If this sounds familiar, its because you have been using a simplified syntax for location constraint rules already. Consider the following location constraint: .Prevent myApacheRsc from running on c001n03 +===== +[source,XML] ------- ------- +===== This constraint can be more verbosely written as: .Prevent myApacheRsc from running on c001n03 - expanded version +===== +[source,XML] ------- ------- +===== The advantage of using the expanded form is that one can then add extra clauses to the rule, such as limiting the rule such that it only applies during certain times of the day or days of the week (this is discussed in subsequent sections). It also allows us to match on node properties other than its name. If we rated each machine's CPU power such that the cluster had the following nodes section: .A sample nodes section for use with score-attribute +===== +[source,XML] ------- ------- +===== then we could prevent resources from running on underpowered machines with the rule [source,XML] ------- ------- === Using +score-attribute+ Instead of +score+ === When using +score-attribute+ instead of +score+, each node matched by the rule has its score adjusted differently, according to its value for the named node attribute. Thus, in the previous example, if a rule used +score-attribute="cpu_mips"+, +c001n01+ would have its preference to run the resource increased by +1234+ whereas +c001n02+ would have its preference increased by +5678+. == Using Rules to Control Resource Options == Often some cluster nodes will be different from their peers; sometimes these differences (the location of a binary or the names of network interfaces) require resources to be configured differently depending on the machine they're hosted on. By defining multiple +instance_attributes+ objects for the resource and adding a rule to each, we can easily handle these special cases. In the example below, +mySpecialRsc+ will use eth1 and port 9999 when run on +node1+, eth2 and port 8888 on +node2+ and default to eth0 and port 9999 for all other nodes. .Defining different resource options based on the node name +===== +[source,XML] ------- ------- +===== The order in which +instance_attributes+ objects are evaluated is determined by their score (highest to lowest). If not supplied, score defaults to zero and objects with an equal score are processed in listed order. If the +instance_attributes+ object does not have a +rule+ or has a +rule+ that evaluates to +true+, then for any parameter the resource does not yet have a value for, the resource will use the parameter values defined by the +instance_attributes+ object. == Using Rules to Control Cluster Options == indexterm:[Rule,Controlling Cluster Options] indexterm:[Cluster Options,Controlled by Rules] Controlling cluster options is achieved in much the same manner as specifying different resource options on different nodes. The difference is that because they are cluster options, one cannot (or should not, because they won't work) use attribute based expressions. The following example illustrates how to set a different +resource-stickiness+ value during and outside of work hours. This allows resources to automatically move back to their most preferred hosts, but at a time that (in theory) does not interfere with business activities. .Change +resource-stickiness+ during working hours +===== +[source,XML] ------- ------- +===== == Ensuring Time Based Rules Take Effect == anchor:s-rules-recheck[Ensuring Time Based Rules Take Effect] A Pacemaker cluster is an event driven system. As such, it won't recalculate the best place for resources to run in unless something (like a resource failure or configuration change) happens. This can mean that a location constraint that only allows resource X to run between 9am and 5pm is not enforced. If you rely on time based rules, it is essential that you set the +cluster-recheck-interval+ option. This tells the cluster to periodically recalculate the ideal state of the cluster. For example, if you set +cluster-recheck-interval=5m+, then sometime between 9:00 and 9:05 the cluster would notice that it needs to start resource X, and between 17:00 and 17:05 it would realize that X needed to be stopped. Note that the timing of the actual start and stop actions depends on what else needs to be performed first. diff --git a/doc/Pacemaker_Explained/en-US/Ch-Status.txt b/doc/Pacemaker_Explained/en-US/Ch-Status.txt index 44f6b46edf..7ef577dd87 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Status.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Status.txt @@ -1,371 +1,377 @@ = Status - Here be dragons = Most users never need to understand the contents of the status section and can be happy with the output from `crm_mon`. However for those with a curious inclination, this section attempts to provide an overview of its contents. == Node Status == indexterm:[Node,Status] indexterm:[Status of a Node] In addition to the cluster's configuration, the CIB holds an up-to-date representation of each cluster node in the status section. .A bare-bones status entry for a healthy node called +cl-virt-1+ +====== [source,XML] ----- ----- - - +====== Users are highly recommended _not to modify_ any part of a node's state _directly_. The cluster will periodically regenerate the entire section from authoritative sources. So any changes should be done with the tools for those subsystems. .Authoritative Sources for State Information [width="95%",cols="5m,5<",options="header",align="center"] |========================================================= |Dataset |Authoritative Source |node_state fields |crmd |transient_attributes tag |attrd |lrm tag |lrmd |========================================================= The fields used in the +node_state+ objects are named as they are largely for historical reasons and are rooted in Pacemaker's origins as the Heartbeat resource manager. They have remained unchanged to preserve compatibility with older versions. .Node Status Fields [width="95%",cols="2m,5<",options="header",align="center"] |========================================================= |Field |Description | id | indexterm:[id,Node Status Field] -indexterm:[>Node,Status Field,id] +indexterm:[Node,Status Field,id] Unique identifier for the node. Corosync based clusters use the uname of the machine, Heartbeat clusters use a human-readable (but annoying) UUID. | uname | indexterm:[uname Node Status Field] -indexterm:[>Node,Status Field,uname] +indexterm:[Node,Status Field,uname] The node's machine name (output from `uname -n`). | ha | indexterm:[ha Node Status Field] -indexterm:[>Node,Status Field,ha] +indexterm:[Node,Status Field,ha] Flag specifying whether the cluster software is active on the node. Allowed values: +active+, +dead+. | in_ccm | indexterm:[in_ccm Node Status Field] -indexterm:[>Node,Status Field,in_ccm] +indexterm:[Node,Status Field,in_ccm] Flag for cluster membership; allowed values: +true+, +false+. | crmd | indexterm:[crmd Node Status Field] -indexterm:[>Node,Status Field,crmd] +indexterm:[Node,Status Field,crmd] Flag: is the crmd process active on the node? One of +online+, +offline+. | join | indexterm:[join Node Status Field] -indexterm:[>Node,Status Field,join] +indexterm:[Node,Status Field,join] Flag saying whether the node participates in hosting resources. Possible values: +down+, +pending+, +member+, +banned+. | expected | indexterm:[expected Node Status Field] -indexterm:[>Node,Status Field,expected] +indexterm:[Node,Status Field,expected] Expected value for +join+. | crm-debug-origin | indexterm:[crm-debug-origin Node Status Field] -indexterm:[>Node,Status Field,crm-debug-origin] +indexterm:[Node,Status Field,crm-debug-origin] Diagnostic indicator: the origin of the most recent change(s). |========================================================= The cluster uses these fields to determine if, at the node level, the node is healthy or is in a failed state and needs to be fenced. == Transient Node Attributes == Like regular xref:s-node-attributes[node attributes], the name/value pairs listed here also help to describe the node. However they are forgotten by the cluster when the node goes offline. This can be useful, for instance, when you want a node to be in standby mode (not able to run resources) until the next reboot. In addition to any values the administrator sets, the cluster will also store information about failed resources here. .Example set of transient node attributes for node "cl-virt-1" +====== [source,XML] ----- ----- +====== In the above example, we can see that the +pingd:0+ resource has failed once, at +Mon Apr 6 11:22:22 2009+. footnote:[ You can use the standard +date+ command to print a human readable of any seconds-since-epoch value: # `date -d @number` ] We also see that the node is connected to three "pingd" peers and that all known resources have been checked for on this machine (+probe_complete+). == Operation History == indexterm:[Operation History] A node's resource history is held in the +lrm_resources+ tag (a child of the +lrm+ tag). The information stored here includes enough information for the cluster to stop the resource safely if it is removed from the +configuration+ section. Specifically the resource's +id+, +class+, +type+ and +provider+ are stored. .A record of the apcstonith resource +====== [source,XML] ------ ------ +====== Additionally, we store the last job for every combination of +resource, action+ and +interval+. The concatenation of the values in this tuple are used to create the id of the +lrm_rsc_op+ object. .Contents of an +lrm_rsc_op+ job [width="95%",cols="2m,5<",options="header",align="center"] |========================================================= |Field |Description | id | indexterm:[id,Job Field] -indexterm:[>Job Field,id] +indexterm:[Job Field,id] Identifier for the job constructed from the resource's +id+, +operation+ and +interval+. | call-id | indexterm:[call-id Job Field] -indexterm:[>Job Field,call-id] +indexterm:[Job Field,call-id] The job's ticket number. Used as a sort key to determine the order in which the jobs were executed. | operation | indexterm:[operation Job Field] -indexterm:[>Job Field,operation] +indexterm:[Job Field,operation] The action the resource agent was invoked with. | interval | indexterm:[interval Job Field] -indexterm:[>Job Field,interval] +indexterm:[Job Field,interval] The frequency, in milliseconds, at which the operation will be repeated. A one-off job is indicated by 0. | op-status | indexterm:[op-status Job Field] -indexterm:[>Job Field,op-status] +indexterm:[Job Field,op-status] The job's status. Generally this will be either 0 (done) or -1 (pending). Rarely used in favor of +rc-code+. | rc-code | indexterm:[rc-code Job Field] -indexterm:[>Job Field,rc-code] +indexterm:[Job Field,rc-code] The job's result. Refer to xref:s-ocf-return-codes[] for details on what the values here mean and how they are interpreted. | last-run | indexterm:[last-run Job Field] -indexterm:[>Job Field,last-run] +indexterm:[Job Field,last-run] Diagnostic indicator. Machine local date/time, in seconds since epoch, at which the job was executed. | last-rc-change | indexterm:[last-rc-change Job Field] -indexterm:[>Job Field,last-rc-change] +indexterm:[Job Field,last-rc-change] Diagnostic indicator. Machine local date/time, in seconds since epoch, at which the job first returned the current value of +rc-code+. | exec-time | indexterm:[exec-time Job Field] -indexterm:[>Job Field,exec-time] +indexterm:[Job Field,exec-time] Diagnostic indicator. Time, in milliseconds, that the job was running for. | queue-time | indexterm:[queue-time Job Field] -indexterm:[>Job Field,queue-time] +indexterm:[Job Field,queue-time] Diagnostic indicator. Time, in seconds, that the job was queued for in the LRMd. | crm_feature_set | indexterm:[crm_feature_set Job Field] -indexterm:[>Job Field,crm_feature_set] +indexterm:[Job Field,crm_feature_set] The version which this job description conforms to. Used when processing +op-digest+. | transition-key | indexterm:[transition-key Job Field] -indexterm:[>Job Field,transition-key] +indexterm:[Job Field,transition-key] A concatenation of the job's graph action number, the graph number, the expected result and the UUID of the crmd instance that scheduled it. This is used to construct +transition-magic+ (below). | transition-magic | indexterm:[transition-magic Job Field] -indexterm:[>Job Field,transition-magic] +indexterm:[Job Field,transition-magic] A concatenation of the job's +op-status+, +rc-code+ and +transition-key+. Guaranteed to be unique for the life of the cluster (which ensures it is part of CIB update notifications) and contains all the information needed for the crmd to correctly analyze and process the completed job. Most importantly, the decomposed elements tell the crmd if the job entry was expected and whether it failed. | op-digest | indexterm:[op-digest Job Field] -indexterm:[>Job Field,op-digest] +indexterm:[Job Field,op-digest] An MD5 sum representing the parameters passed to the job. Used to detect changes to the configuration, to restart resources if necessary. | crm-debug-origin | indexterm:[crm-debug-origin Job Field] -indexterm:[>Job Field,crm-debug-origin] +indexterm:[Job Field,crm-debug-origin] Diagnostic indicator. The origin of the current values. |========================================================= === Simple Example === .A monitor operation (determines current state of the apcstonith resource) +====== [source,XML] ----- ----- +====== In the above example, the job is a non-recurring monitor operation often referred to as a "probe" for the +apcstonith+ resource. The cluster schedules probes for every configured resource on when a new node starts, in order to determine the resource's current state before it takes any further action. From the +transition-key+, we can see that this was the 22nd action of the 2nd graph produced by this instance of the crmd (2668bbeb-06d5-40f9-936d-24cb7f87006a). The third field of the +transition-key+ contains a 7, this indicates that the job expects to find the resource inactive. By looking at the +rc-code+ property, we see that this was the case. As that is the only job recorded for this node we can conclude that the cluster started the resource elsewhere. === Complex Resource History Example === .Resource history of a pingd clone with multiple jobs +====== [source,XML] ----- ----- +====== When more than one job record exists, it is important to first sort them by +call-id+ before interpreting them. Once sorted, the above example can be summarized as: . A non-recurring monitor operation returning 7 (not running), with a +call-id+ of 3 . A stop operation returning 0 (success), with a +call-id+ of 32 . A start operation returning 0 (success), with a +call-id+ of 33 . A recurring monitor returning 0 (success), with a +call-id+ of 34 The cluster processes each job record to build up a picture of the resource's state. After the first and second entries, it is considered stopped and after the third it considered active. Based on the last operation, we can tell that the resource is currently active. Additionally, from the presence of a +stop+ operation with a lower +call-id+ than that of the +start+ operation, we can conclude that the resource has been restarted. Specifically this occurred as part of actions 11 and 31 of transition 11 from the crmd instance with the key +2668bbeb...+. This information can be helpful for locating the relevant section of the logs when looking for the source of a failure. diff --git a/doc/Pacemaker_Explained/en-US/Ch-Stonith.txt b/doc/Pacemaker_Explained/en-US/Ch-Stonith.txt index f7a30a0c0f..b33819d4d5 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Stonith.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Stonith.txt @@ -1,307 +1,307 @@ = Configure STONITH = == What Is STONITH == anchor:ch-stonith[Configuring STONITH] STONITH is an acronym for Shoot-The-Other-Node-In-The-Head and it protects your data from being corrupted by rogue nodes or concurrent access. Just because a node is unresponsive, this doesn't mean it isn't accessing your data. The only way to be 100% sure that your data is safe, is to use STONITH so we can be certain that the node is truly offline, before allowing the data to be accessed from another node. STONITH also has a role to play in the event that a clustered service cannot be stopped. In this case, the cluster uses STONITH to force the whole node offline, thereby making it safe to start the service elsewhere. == What STONITH Device Should You Use == It is crucial that the STONITH device can allow the cluster to differentiate between a node failure and a network one. The biggest mistake people make in choosing a STONITH device is to use remote power switch (such as many on-board IMPI controllers) that shares power with the node it controls. In such cases, the cluster cannot be sure if the node is really offline, or active and suffering from a network fault. Likewise, any device that relies on the machine being active (such as SSH-based "devices" used during testing) are inappropriate. == Configuring STONITH == ifdef::pcs[] . Find the correct driver: +pcs stonith list+ . Find the parameters associated with the device: +pcs stonith describe + . Create a local config to make changes to +pcs cluster cib stonith_cfg+ . Create the fencing resource using +pcs -f stonith_cfg stonith create [stonith device options]+ . Set stonith-enable to true. +pcs -f stonith_cfg property set stonith-enabled=true+ endif::[] ifdef::crm[] . Find the correct driver: +stonith_admin --list-installed+ . Since every device is different, the parameters needed to configure it will vary. To find out the parameters associated with the device, run: +stonith_admin --metadata --agent type+ The output should be XML formatted text containing additional parameter descriptions. We will endevor to make the output more friendly in a later version. . Enter the shell crm Create an editable copy of the existing configuration +cib new stonith+ Create a fencing resource containing a primitive resource with a class of stonith, a type of type and a parameter for each of the values returned in step 2: +configure primitive ...+ endif::[] . If the device does not know how to fence nodes based on their uname, you may also need to set the special +pcmk_host_map+ parameter. See +man stonithd+ for details. . If the device does not support the list command, you may also need to set the special +pcmk_host_list+ and/or +pcmk_host_check+ parameters. See +man stonithd+ for details. . If the device does not expect the victim to be specified with the port parameter, you may also need to set the special +pcmk_host_argument+ parameter. See +man stonithd+ for details. ifdef::crm[] . Upload it into the CIB from the shell: +cib commit stonith+ endif::[] ifdef::pcs[] . Commit the new configuration. +pcs cluster push cib stonith_cfg+ endif::[] . Once the stonith resource is running, you can test it by executing: +stonith_admin --reboot nodename+. Although you might want to stop the cluster on that machine first. == Example == Assuming we have an chassis containing four nodes and an IPMI device active on 10.0.0.1, then we would chose the fence_ipmilan driver in step 2 and obtain the following list of parameters .Obtaining a list of STONITH Parameters ifdef::pcs[] [source,Bash] ---- # pcs stonith describe fence_ipmilan Stonith options for: fence_ipmilan auth: IPMI Lan Auth type (md5, password, or none) ipaddr: IPMI Lan IP to talk to passwd: Password (if required) to control power on IPMI device passwd_script: Script to retrieve password (if required) lanplus: Use Lanplus login: Username/Login (if required) to control power on IPMI device action: Operation to perform. Valid operations: on, off, reboot, status, list, diag, monitor or metadata timeout: Timeout (sec) for IPMI operation cipher: Ciphersuite to use (same as ipmitool -C parameter) method: Method to fence (onoff or cycle) power_wait: Wait X seconds after on/off operation delay: Wait X seconds before fencing is started privlvl: Privilege level on IPMI device verbose: Verbose mode ---- endif::[] ifdef::crm[] -[source,Bash] +[source,C] ---- # stonith_admin --metadata -a fence_ipmilan ---- [source,XML] ---- fence_ipmilan is an I/O Fencing agent which can be used with machines controlled by IPMI. This agent calls support software using ipmitool (http://ipmitool.sf.net/). To use fence_ipmilan with HP iLO 3 you have to enable lanplus option (lanplus / -P) and increase wait after operation to 4 seconds (power_wait=4 / -T 4) IPMI Lan Auth type (md5, password, or none) IPMI Lan IP to talk to Password (if required) to control power on IPMI device Script to retrieve password (if required) Use Lanplus Username/Login (if required) to control power on IPMI device Operation to perform. Valid operations: on, off, reboot, status, list, diag, monitor or metadata Timeout (sec) for IPMI operation Ciphersuite to use (same as ipmitool -C parameter) Method to fence (onoff or cycle) Wait X seconds after on/off operation Wait X seconds before fencing is started Verbose mode ---- endif::[] from which we would create a STONITH resource fragment that might look like this .Sample STONITH Resource ifdef::pcs[] [source,Bash] ---- # pcs cluster cib stonith_cfg # pcs -f stonith_cfg stonith create impi-fencing fence_ipmilan \ pcmk_host_list="pcmk-1 pcmk-2" ipaddr=10.0.0.1 login=testuser \ passwd=acd123 op monitor interval=60s # pcs -f stonith_cfg stonith impi-fencing (stonith:fence_ipmilan) Stopped ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm crm(live)# cib new stonith INFO: stonith shadow CIB created crm(stonith)# configure primitive impi-fencing stonith::fence_ipmilan \ params pcmk_host_list="pcmk-1 pcmk-2" ipaddr=10.0.0.1 login=testuser passwd=abc123 \ op monitor interval="60s" ---- endif::[] And finally, since we disabled it earlier, we need to re-enable STONITH. At this point we should have the following configuration. ifdef::pcs[] [source,Bash] ---- # pcs -f stonith_cfg property set stonith-enabled=true # pcs -f stonith_cfg property dc-version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 cluster-infrastructure: corosync no-quorum-policy: ignore stonith-enabled: true ---- Now push the configuration into the cluster. ifdef::pcs[] -[source,Bash] +[source,C] ---- # pcs cluster push cib stonith_cfg ---- endif::[] ifdef::crm[] [source,Bash] ---- crm(stonith)# configure property stonith-enabled="true" crm(stonith)# configure shownode pcmk-1 node pcmk-2 primitive WebData ocf:linbit:drbd \ params drbd_resource="wwwdata" \ op monitor interval="60s" primitive WebFS ocf:heartbeat:Filesystem \ params device="/dev/drbd/by-res/wwwdata" directory="/var/www/html" fstype="gfs2" primitive WebSite ocf:heartbeat:apache \ params configfile="/etc/httpd/conf/httpd.conf" \ op monitor interval="1min" primitive ClusterIP ocf:heartbeat:IPaddr2 \ params ip="192.168.122.101" cidr_netmask="32" clusterip_hash="sourceip" \ op monitor interval="30s"primitive ipmi-fencing stonith::fence_ipmilan \ params pcmk_host_list="pcmk-1 pcmk-2" ipaddr=10.0.0.1 login=testuser passwd=abc123 \ op monitor interval="60s"ms WebDataClone WebData \ meta master-max="2" master-node-max="1" clone-max="2" clone-node-max="1" notify="true" clone WebFSClone WebFS clone WebIP ClusterIP \ meta globally-unique="true" clone-max="2" clone-node-max="2" clone WebSiteClone WebSite colocation WebSite-with-WebFS inf: WebSiteClone WebFSClone colocation fs_on_drbd inf: WebFSClone WebDataClone:Master colocation website-with-ip inf: WebSiteClone WebIP order WebFS-after-WebData inf: WebDataClone:promote WebFSClone:start order WebSite-after-WebFS inf: WebFSClone WebSiteClone order apache-after-ip inf: WebIP WebSiteClone property $id="cib-bootstrap-options" \ dc-version="1.1.5-bdd89e69ba545404d02445be1f3d72e6a203ba2f" \ cluster-infrastructure="openais" \ expected-quorum-votes="2" \ stonith-enabled="true" \ no-quorum-policy="ignore" rsc_defaults $id="rsc-options" \ resource-stickiness="100" crm(stonith)# cib commit stonithINFO: commited 'stonith' shadow CIB to the cluster crm(stonith)# quit bye ---- endif::[] diff --git a/doc/Pacemaker_Explained/en-US/Ch-Utilization.txt b/doc/Pacemaker_Explained/en-US/Ch-Utilization.txt index c95d7c7514..6eeb063a8a 100644 --- a/doc/Pacemaker_Explained/en-US/Ch-Utilization.txt +++ b/doc/Pacemaker_Explained/en-US/Ch-Utilization.txt @@ -1,225 +1,221 @@ = Utilization and Placement Strategy = == Background == Pacemaker decides where to place a resource according to the resource allocation scores on every node. The resource will be allocated to the node where the resource has the highest score. If the resource allocation scores on all the nodes are equal, by the `default` placement strategy, Pacemaker will choose a node with the least number of allocated resources for balancing the load. If the number of resources on each node is equal, the first eligible node listed in cib will be chosen to run the resource. Though resources are different. They may consume different amounts of the capacities of the nodes. Actually, we cannot ideally balance the load just according to the number of resources allocated to a node. Besides, if resources are placed such that their combined requirements exceed the provided capacity, they may fail to start completely or run with degraded performance. To take these into account, Pacemaker allows you to specify the following configurations: . The `capacity` a certain `node provides`. - . The `capacity` a certain `resource requires`. - . An overall `strategy` for placement of resources. == Utilization attributes == To configure the capacity a node provides and the resource's requirements, use `utilization` attributes. You can name the `utilization` attributes according to your preferences and define as many `name/value` pairs as your configuration needs. However, the attribute's values must be `integers`. First, specify the capacities the nodes provide: [source,XML] ---- - - - - - - - - - - - - + + + + + + + + + + + + ---- Then, specify the capacities the resources require: [source,XML] ---- - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + ---- A node is considered eligible for a resource if it has sufficient free capacity to satisfy the resource's requirements. The nature of the required or provided capacities is completely irrelevant for Pacemaker, it just makes sure that all capacity requirements of a resource are satisfied before placing a resource to a node. == Placement Strategy == After you have configured the capacities your nodes provide and the capacities your resources require, you need to set the `placement-strategy` in the global cluster options, otherwise the capacity configurations have `no effect`. Four values are available for the `placement-strategy`: `default`:: Utilization values are not taken into account at all, per default. Resources are allocated according to allocation scores. If scores are equal, resources are evenly distributed across nodes. `utilization`:: Utilization values are taken into account when deciding whether a node is considered eligible if it has sufficient free capacity to satisfy the resource's requirements. However, load-balancing is still done based on the number of resources allocated to a node. `balanced`:: Utilization values are taken into account when deciding whether a node is eligible to serve a resource; an attempt is made to spread the resources evenly, optimizing resource performance. `minimal`:: Utilization values are taken into account when deciding whether a node is eligible to serve a resource; an attempt is made to concentrate the resources on as few nodes as possible, thereby enabling possible power savings on the remaining nodes. Set `placement-strategy` with `crm_attribute`: -[source,Bash] ----- +[source,C] # crm_attribute --attr-name placement-strategy --attr-value balanced ----- Now Pacemaker will ensure the load from your resources will be distributed evenly throughout the cluster - without the need for convoluted sets of colocation constraints. == Allocation Details == === Which node is preferred to be chosen to get consumed first on allocating resources? === - The node that is most healthy (which has the highest node weight) gets consumed first. - If their weights are equal: * If `placement-strategy="default|utilization"`, the node that has the least number of allocated resources gets consumed first. ** If their numbers of allocated resources are equal, the first eligible node listed in cib gets consumed first. * If `placement-strategy="balanced"`, the node that has more free capacity gets consumed first. ** If the free capacities of the nodes are equal, the node that has the least number of allocated resources gets consumed first. *** If their numbers of allocated resources are equal, the first eligible node listed in cib gets consumed first. * If `placement-strategy="minimal"`, the first eligible node listed in cib gets consumed first. ==== Which node has more free capacity? ==== This will be quite clear if we only define one type of `capacity`. While if we define multiple types of `capacity`, for example: - If `nodeA` has more free `cpus`, `nodeB` has more free `memory`, their free capacities are equal. - If `nodeA` has more free `cpus`, while `nodeB` has more free `memory` and `storage`, `nodeB` has more free capacity. === Which resource is preferred to be chosen to get assigned first? === - The resource that has the highest priority gets allocated first. - If their priorities are equal, check if they are already running. The resource that has the highest score on the node where it's running gets allocated first (to prevent resource shuffling). - If the scores above are equal or they are not running, the resource has the highest score on the preferred node gets allocated first. - If the scores above are equal, the first runnable resource listed in cib gets allocated first. == Limitations == This type of problem Pacemaker is dealing with here is known as the http://en.wikipedia.org/wiki/Knapsack_problem[knapsack problem] and falls into the http://en.wikipedia.org/wiki/NP-complete[NP-complete] category of computer science problems - which is fancy way of saying "it takes a really long time to solve". Clearly in a HA cluster, it's not acceptable to spend minutes, let alone hours or days, finding an optional solution while services remain unavailable. So instead of trying to solve the problem completely, Pacemaker uses a 'best effort' algorithm for determining which node should host a particular service. This means it arrives at a solution much faster than traditional linear programming algorithms, but by doing so at the price of leaving some services stopped. In the contrived example above: - `rsc-small` would be allocated to `node1` - `rsc-medium` would be allocated to `node2` - `rsc-large` would remain inactive Which is not ideal. == Strategies for Dealing with the Limitations == - Ensure you have sufficient physical capacity. It might sounds obvious, but if the physical capacity of your nodes is (close to) maxed out by the cluster under normal conditions, then failover isn't going to go well. Even without the Utilization feature, you'll start hitting timeouts and getting secondary failures'. - Build some buffer into the capabilities advertised by the nodes. Advertise slightly more resources than we physically have on the (usually valid) assumption that a resource will not use 100% of the configured number of cpu/memory/etc `all` the time. This practice is also known as 'over commit'. - Specify resource priorities. If the cluster is going to sacrifice services, it should be the ones you care (comparatively) about the least. Ensure that resource priorities are properly set so that your most important resources are scheduled first. diff --git a/doc/Pacemaker_Explained/en-US/Revision_History.xml b/doc/Pacemaker_Explained/en-US/Revision_History.xml index 2cb4df7244..a351d9c6cd 100644 --- a/doc/Pacemaker_Explained/en-US/Revision_History.xml +++ b/doc/Pacemaker_Explained/en-US/Revision_History.xml @@ -1,46 +1,47 @@ Revision History 1 19 Oct 2009 AndrewBeekhofandrew@beekhof.net Import from Pages.app 2 26 Oct 2009 AndrewBeekhofandrew@beekhof.net Cleanup and reformatting of docbook xml complete 3 Tue Nov 12 2009 AndrewBeekhofandrew@beekhof.net Split book into chapters and pass validation Re-organize book for use with Publican 4 Mon Oct 8 2012 AndrewBeekhofandrew@beekhof.net - Converted to asciidoc (which is converted to docbook for - use with Publican + Converted to asciidoc + (which is converted to docbook for use with + Publican) diff --git a/doc/asciidoc.reference b/doc/asciidoc.reference index bc726bc249..c2476e3c5f 100644 --- a/doc/asciidoc.reference +++ b/doc/asciidoc.reference @@ -1,20 +1,44 @@ See also: http://powerman.name/doc/asciidoc Commands: `some-tool --with option` Files: '/tmp/file.name' Italic: _some text_ Mono: +some text+ Bold: *some text* Super: ^some text^ Sub: ~some text~ Quotes: ``double quoted'' `single quoted' Tool: command Literal: mono Varname: mono Option: italic Emphasis: italic bold Replaceable: italic mono + + +.Title for Eaxmple +===== +Some text +===== + +.Title for Eaxmple with XML Listing +===== +[source,XML] +----- + +----- +===== + +Naked code listing: +(Use 'C' and a leading '#' instead of 'Bash' when commands are being show) + +[source,C] +----- +# some command --here +----- + +