diff --git a/doc/Clusters_from_Scratch/en-US/Ch-Active-Passive.txt b/doc/Clusters_from_Scratch/en-US/Ch-Active-Passive.txt index 7375dc8850..c858bca057 100644 --- a/doc/Clusters_from_Scratch/en-US/Ch-Active-Passive.txt +++ b/doc/Clusters_from_Scratch/en-US/Ch-Active-Passive.txt @@ -1,669 +1,673 @@ = Creating an Active/Passive Cluster = == Exploring the Existing Configuration == When Pacemaker starts up, it automatically records the number and details of the nodes in the cluster as well as which stack is being used and the version of Pacemaker being used. This is what the base configuration should look like. ifdef::pcs[] [source,Bash] ---- # pcs status Last updated: Fri Sep 14 10:12:01 2012 Last change: Fri Sep 14 09:51:55 2012 via crmd on pcmk-2 Stack: corosync Current DC: pcmk-1 (1) - partition with quorum Version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 2 Nodes configured, unknown expected votes 0 Resources configured. Online: [ pcmk-1 pcmk-2 ] Full list of resources: ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm configure show node $id="1702537408" pcmk-1 node $id="1719314624" pcmk-2 property $id="cib-bootstrap-options" \ dc-version="1.1.7-2.fc17-ee0730e13d124c3d58f00016c3376a1de5323cff" \ cluster-infrastructure="corosync" ---- endif::[] +ifdef::pcs[] + For those that are not of afraid of XML, you can see the raw cluster configuration and status by using the +pcs cluster cib+ command. .The last XML you'll see in this document -ifdef::pcs[] [source,Bash] ---- # pcs cluster cib ---- endif::[] ifdef::crm[] +For those that are not of afraid of XML, you can see the raw configuration by appending "xml" to the previous command. + +.The last XML you'll see in this document [source,Bash] ---- # crm configure show xml ---- endif::[] Before we make any changes, its a good idea to check the validity of the configuration. [source,Bash] ---- # crm_verify -L -V error: unpack_resources: Resource start-up disabled since no STONITH resources have been defined error: unpack_resources: Either configure some or disable STONITH with the stonith-enabled option error: unpack_resources: NOTE: Clusters with shared data need STONITH to ensure data integrity Errors found during check: config not valid -V may provide more details ---- As you can see, the tool has found some errors. In order to guarantee the safety of your data footnote:[If the data is corrupt, there is little point in continuing to make it available] , the default for STONITH footnote:[A common node fencing mechanism. Used to ensure data integrity by powering off "bad" nodes] in Pacemaker is +enabled+. However it also knows when no STONITH configuration has been supplied and reports this as a problem (since the cluster would not be able to make progress if a situation requiring node fencing arose). For now, we will disable this feature and configure it later in the Configuring STONITH section. It is important to note that the use of STONITH is highly encouraged, turning it off tells the cluster to simply pretend that failed nodes are safely powered off. Some vendors will even refuse to support clusters that have it disabled. To disable STONITH, we set the _stonith-enabled_ cluster option to false. ifdef::pcs[] [source,Bash] ---- # pcs property set stonith-enabled=false # crm_verify -L ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm configure property stonith-enabled=false # crm_verify -L ---- endif::[] With the new cluster option set, the configuration is now valid. [WARNING] ========= The use of stonith-enabled=false is completely inappropriate for a production cluster. We use it here to defer the discussion of its configuration which can differ widely from one installation to the next. See <<_what_is_stonith>> for information on why STONITH is important and details on how to configure it. ========= == Adding a Resource == The first thing we should do is configure an IP address. Regardless of where the cluster service(s) are running, we need a consistent address to contact them on. Here I will choose and add 192.168.122.120 as the floating address, give it the imaginative name ClusterIP and tell the cluster to check that its running every 30 seconds. [IMPORTANT] =========== The chosen address must not be one already associated with a physical node =========== ifdef::pcs[] [source,Bash] ---- # pcs resource create ClusterIP ocf:heartbeat:IPaddr2 \ ip=192.168.0.120 cidr_netmask=32 op monitor interval=30s ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm configure primitive ClusterIP ocf:heartbeat:IPaddr2 \ params ip=192.168.122.120 cidr_netmask=32 \ op monitor interval=30s ---- endif::[] The other important piece of information here is ocf:heartbeat:IPaddr2. This tells Pacemaker three things about the resource you want to add. The first field, ocf, is the standard to which the resource script conforms to and where to find it. The second field is specific to OCF resources and tells the cluster which namespace to find the resource script in, in this case heartbeat. The last field indicates the name of the resource script. ifdef::pcs[] To obtain a list of the available resource standards (the ocf part of ocf:heartbeat:IPaddr2), run [source,Bash] ---- # pcs resource standards ocf lsb service systemd stonith ---- To obtain a list of the available ocf resource providers (the heartbeat part of ocf:heartbeat:IPaddr2), run [source,Bash] ---- # pcs resource providers heartbeat linbit pacemaker redhat ---- Finally, if you want to see all the resource agents available for a specific ocf provider (the IPaddr2 part of ocf:heartbeat:IPaddr2), run [source,Bash] ---- # pcs resource agents ocf:heartbeat AoEtarget AudibleAlarm CTDB ClusterMon Delay Dummy . . (skipping lots of resources to save space) . IPaddr2 . . . symlink syslog-ng tomcat vmware ---- endif::[] ifdef::crm[] To obtain a list of the available resource classes, run [source,Bash] ---- # crm ra classes heartbeat lsb ocf / heartbeat pacemaker stonith ---- To then find all the OCF resource agents provided by Pacemaker and Heartbeat, run [source,Bash] ---- # crm ra list ocf pacemaker ClusterMon Dummy HealthCPU HealthSMART Stateful SysInfo SystemHealth controld o2cb ping pingd # crm ra list ocf heartbeat AoEtarget AudibleAlarm CTDB ClusterMon Delay Dummy EvmsSCC Evmsd Filesystem ICP IPaddr IPaddr2 IPsrcaddr IPv6addr LVM LinuxSCSI MailTo ManageRAID ManageVE Pure-FTPd Raid1 Route SAPDatabase SAPInstance SendArp ServeRAID SphinxSearchDaemon Squid Stateful SysInfo VIPArip VirtualDomain WAS WAS6 WinPopup Xen Xinetd anything apache conntrackd db2 drbd eDir88 ethmonitor exportfs fio iSCSILogicalUnit iSCSITarget ids iscsi jboss ldirectord lxc mysql mysql-proxy nfsserver nginx oracle oralsnr pgsql pingd portblock postfix proftpd rsyncd scsi2reservation sfex symlink syslog-ng tomcat vmware ---- endif::[] Now verify that the IP resource has been added and display the cluster's status to see that it is now active. ifdef::pcs[] [source,Bash] ---- # pcs status Last updated: Fri Sep 14 10:17:00 2012 Last change: Fri Sep 14 10:15:48 2012 via cibadmin on pcmk-1 Stack: corosync Current DC: pcmk-1 (1) - partition with quorum Version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 2 Nodes configured, unknown expected votes 1 Resources configured. Online: [ pcmk-1 pcmk-2 ] Full list of resources: ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm configure show node $id="1702537408" pcmk-1 node $id="1719314624" pcmk-2 primitive ClusterIP ocf:heartbeat:IPaddr2 \ params ip="192.168.122.120" cidr_netmask="32" \ op monitor interval="30s" property $id="cib-bootstrap-options" \ dc-version="1.1.7-2.fc17-ee0730e13d124c3d58f00016c3376a1de5323cff" \ cluster-infrastructure="corosync" \ stonith-enabled="false" # crm_mon -1 ============ Last updated: Tue Apr 3 09:56:50 2012 Last change: Tue Apr 3 09:54:37 2012 via cibadmin on pcmk-1 Stack: corosync Current DC: pcmk-1 (1702537408) - partition with quorum Version: 1.1.7-2.fc17-ee0730e13d124c3d58f00016c3376a1de5323cff 2 Nodes configured, unknown expected votes 1 Resources configured. ============ Online: [ pcmk-1 pcmk-2 ] ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 ---- endif::[] == Perform a Failover == Being a high-availability cluster, we should test failover of our new resource before moving on. First, find the node on which the IP address is running. ifdef::pcs[] [source,Bash] ---- # pcs status Last updated: Fri Sep 14 10:17:00 2012 Last change: Fri Sep 14 10:15:48 2012 via cibadmin on pcmk-1 Stack: corosync Current DC: pcmk-1 (1) - partition with quorum Version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 2 Nodes configured, unknown expected votes 1 Resources configured. Online: [ pcmk-1 pcmk-2 ] Full list of resources: ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm resource status ClusterIP resource ClusterIP is running on: pcmk-1 ---- endif::[] Shut down Pacemaker and Corosync on that machine. ifdef::pcs[] [source,Bash] ---- #pcs cluster stop pcmk-1 Stopping Cluster... ---- Once Corosync is no longer running, go to the other node and check the cluster status. [source,Bash] ---- # pcs status Last updated: Fri Sep 14 10:31:01 2012 Last change: Fri Sep 14 10:15:48 2012 via cibadmin on pcmk-1 Stack: corosync Current DC: pcmk-2 (2) - partition WITHOUT quorum Version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 2 Nodes configured, unknown expected votes 1 Resources configured. Online: [ pcmk-2 ] OFFLINE: [ pcmk-1 ] Full list of resources: ClusterIP (ocf::heartbeat:IPaddr2): Stopped ---- endif::[] ifdef::crm[] [source,Bash] ---- # ssh pcmk-1 -- service pacemaker stop # ssh pcmk-1 -- service corosync stop ---- Once Corosync is no longer running, go to the other node and check the cluster status with crm_mon. [source,Bash] ---- # crm_mon -1 ============ Last updated: Tue Apr 3 10:01:28 2012 Last change: Tue Apr 3 09:54:39 2012 via cibadmin on pcmk-1 Stack: corosync Current DC: pcmk-2 (1719314624) - partition WITHOUT quorum Version: 1.1.7-2.fc17-ee0730e13d124c3d58f00016c3376a1de5323cff 2 Nodes configured, unknown expected votes 1 Resources configured. ============ Online: [ pcmk-2 ] OFFLINE: [ pcmk-1 ] ---- endif::[] There are three things to notice about the cluster's current state. The first is that, as expected, +pcmk-1+ is now offline. However we can also see that +ClusterIP+ isn't running anywhere! === Quorum and Two-Node Clusters === This is because the cluster no longer has quorum, as can be seen by the text "partition WITHOUT quorum" in the status output. In order to reduce the possibility of data corruption, Pacemaker's default behavior is to stop all resources if the cluster does not have quorum. A cluster is said to have quorum when more than half the known or expected nodes are online, or for the mathematically inclined, whenever the following equation is true: .... total_nodes < 2 * active_nodes .... Therefore a two-node cluster only has quorum when both nodes are running, which is no longer the case for our cluster. This would normally make the creation of a two-node cluster pointless footnote:[Actually some would argue that two-node clusters are always pointless, but that is an argument for another time] , however it is possible to control how Pacemaker behaves when quorum is lost. In particular, we can tell the cluster to simply ignore quorum altogether. ifdef::pcs[] [source,Bash] ---- # pcs property set no-quorum-policy=ignore # pcs property dc-version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 cluster-infrastructure: corosync stonith-enabled: false no-quorum-policy: ignore ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm configure property no-quorum-policy=ignore # crm configure show node $id="1702537408" pcmk-1 node $id="1719314624" pcmk-2 primitive ClusterIP ocf:heartbeat:IPaddr2 \ params ip="192.168.122.120" cidr_netmask="32" \ op monitor interval="30s" property $id="cib-bootstrap-options" \ dc-version="1.1.7-2.fc17-ee0730e13d124c3d58f00016c3376a1de5323cff" \ cluster-infrastructure="corosync" \ stonith-enabled="false" \ no-quorum-policy="ignore" ---- endif::[] After a few moments, the cluster will start the IP address on the remaining node. Note that the cluster still does not have quorum. ifdef::pcs[] [source,Bash] ---- # pcs status Last updated: Fri Sep 14 10:38:11 2012 Last change: Fri Sep 14 10:37:53 2012 via cibadmin on pcmk-2 Stack: corosync Current DC: pcmk-2 (2) - partition WITHOUT quorum Version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 2 Nodes configured, unknown expected votes 1 Resources configured. Online: [ pcmk-2 ] OFFLINE: [ pcmk-1 ] Full list of resources: ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-2 ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm_mon -1 ============ Last updated: Tue Apr 3 10:02:46 2012 Last change: Tue Apr 3 10:02:08 2012 via cibadmin on pcmk-2 Stack: corosync Current DC: pcmk-2 (1719314624) - partition WITHOUT quorum Version: 1.1.7-2.fc17-ee0730e13d124c3d58f00016c3376a1de5323cff 2 Nodes configured, unknown expected votes 1 Resources configured. ============ Online: [ pcmk-2 ] OFFLINE: [ pcmk-1 ] ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-2 ---- endif::[] Now simulate node recovery by restarting the cluster stack on +pcmk-1+ and check the cluster's status. Note, if you get an authentication error with the 'pcs cluster start pcmk-1' command, you must authenticate on the node using the 'pcs cluster auth pcmk pcmk-1 pcmk-2' command discussed earlier. ifdef::pcs[] [source,Bash] ---- # pcs cluster start pcmk-1 Starting Cluster... # pcs status Last updated: Fri Sep 14 10:42:56 2012 Last change: Fri Sep 14 10:37:53 2012 via cibadmin on pcmk-2 Stack: corosync Current DC: pcmk-2 (2) - partition with quorum Version: 1.1.8-1.el7-60a19ed12fdb4d5c6a6b6767f52e5391e447fec0 2 Nodes configured, unknown expected votes 1 Resources configured. Online: [ pcmk-1 pcmk-2 ] Full list of resources: ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-2 ---- endif::[] ifdef::crm[] [source,Bash] ---- # service corosync start Starting Corosync Cluster Engine (corosync): [ OK ] # service pacemaker start Starting Pacemaker Cluster Manager: [ OK ] # crm_mon ============ Last updated: Fri Aug 28 15:32:13 2009 Stack: openais Current DC: pcmk-2 - partition with quorum Version: 1.1.5-bdd89e69ba545404d02445be1f3d72e6a203ba2f 2 Nodes configured, 2 expected votes 1 Resources configured. ============ Online: [ pcmk-1 pcmk-2 ] ClusterIP (ocf::heartbeat:IPaddr): Started pcmk-2 ---- endif::[] [NOTE] ====== In the dark days, the cluster may have moved the IP back to its original location (+pcmk-1+). Usually this is no longer the case. ====== === Prevent Resources from Moving after Recovery === In most circumstances, it is highly desirable to prevent healthy resources from being moved around the cluster. Moving resources almost always requires a period of downtime. For complex services like Oracle databases, this period can be quite long. To address this, Pacemaker has the concept of resource stickiness which controls how much a service prefers to stay running where it is. You may like to think of it as the "cost" of any downtime. By default, Pacemaker assumes there is zero cost associated with moving resources and will do so to achieve "optimal" footnote:[It should be noted that Pacemaker's definition of optimal may not always agree with that of a human's. The order in which Pacemaker processes lists of resources and nodes creates implicit preferences in situations where the administrator has not explicitly specified them] resource placement. We can specify a different stickiness for every resource, but it is often sufficient to change the default. ifdef::pcs[] [source,Bash] ---- # pcs resource rsc defaults resource-stickiness=100 # pcs resource rsc defaults resource-stickiness: 100 ---- endif::[] ifdef::crm[] [source,Bash] ---- # crm configure rsc_defaults resource-stickiness=100 # crm configure show node $id="1702537408" pcmk-1 node $id="1719314624" pcmk-2 primitive ClusterIP ocf:heartbeat:IPaddr2 \ params ip="192.168.122.120" cidr_netmask="32" \ op monitor interval="30s" property $id="cib-bootstrap-options" \ dc-version="1.1.7-2.fc17-ee0730e13d124c3d58f00016c3376a1de5323cff" \ cluster-infrastructure="corosync" \ stonith-enabled="false" \ no-quorum-policy="ignore" rsc_defaults $id="rsc-options" \ resource-stickiness="100" ---- endif::[]