diff --git a/doc/Clusters_from_Scratch/en-US/Ch-Stonith.txt b/doc/Clusters_from_Scratch/en-US/Ch-Stonith.txt index 6b25b36105..2f85501b14 100644 --- a/doc/Clusters_from_Scratch/en-US/Ch-Stonith.txt +++ b/doc/Clusters_from_Scratch/en-US/Ch-Stonith.txt @@ -1,153 +1,153 @@ = Configure STONITH = == What is STONITH? == STONITH (Shoot The Other Node In The Head aka. fencing) protects your data from being corrupted by rogue nodes or unintended concurrent access. Just because a node is unresponsive doesn't mean it has stopped accessing your data. The only way to be 100% sure that your data is safe, is to use STONITH to ensure 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. == Choose a STONITH Device == It is crucial that your STONITH device can allow the cluster to differentiate between a node failure and a network failure. A common mistake people make when choosing a STONITH device is to use a remote power switch (such as many on-board IPMI controllers) that shares power with the node it controls. If the power fails in such a case, the cluster cannot be sure whether the node is really offline, or active and suffering from a network fault, so the cluster will stop all resources to avoid a possible split-brain situation. Likewise, any device that relies on the machine being active (such as SSH-based "devices" sometimes used during testing) is inappropriate. == Configure the Cluster for STONITH == . Install the STONITH agent(s). To see what packages are available, run `yum search fence-`. Be sure to install the package(s) on all cluster nodes. . Configure the STONITH device itself to be able to fence your nodes and accept fencing requests. This includes any necessary configuration on the device and on the nodes, and any firewall or SELinux changes needed. Test the communication between the device and your nodes. . Find the correct STONITH agent script: `pcs stonith list` . Find the parameters associated with the device: +pcs stonith describe pass:[agent_name]+ . Create a local copy of the CIB: `pcs cluster cib stonith_cfg` . Create the fencing resource: +pcs -f stonith_cfg stonith create pass:[stonith_id stonith_device_type [stonith_device_options]]+ - - If the any flags that do not take arguments, such as `--ssl` should be passed as `ssl=1` ++ +Any flags that do not take arguments, such as +--ssl+, should be passed as +ssl=1+. . Enable STONITH in the cluster: `pcs -f stonith_cfg property set stonith-enabled=true` . 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. . Commit the new configuration: `pcs cluster cib-push stonith_cfg` . Once the STONITH resource is running, test it (you might want to stop the cluster on that machine first): +stonith_admin --reboot pass:[nodename]+ == Example == For this example, assume we have a chassis containing four nodes and an IPMI device active on 10.0.0.1. Following the steps above would go something like this: Step 1: Install the *fence-agents-ipmilan* package on both nodes. Step 2: Configure the IP address, authentication credentials, etc. in the IPMI device itself. Step 3: Choose the *fence_ipmilan* STONITH agent. Step 4: Obtain the agent's possible parameters: ---- [root@pcmk-1 ~]# pcs stonith describe fence_ipmilan Stonith options for: fence_ipmilan ipport: TCP/UDP port to use for connection with device inet6_only: Forces agent to use IPv6 addresses only ipaddr (required): IP Address or Hostname passwd_script: Script to retrieve password method: Method to fence (onoff|cycle) inet4_only: Forces agent to use IPv4 addresses only passwd: Login password or passphrase lanplus: Use Lanplus to improve security of connection auth: IPMI Lan Auth type. cipher: Ciphersuite to use (same as ipmitool -C parameter) privlvl: Privilege level on IPMI device action (required): Fencing Action login: Login Name verbose: Verbose mode debug: Write debug information to given file version: Display version information and exit help: Display help and exit power_wait: Wait X seconds after issuing ON/OFF login_timeout: Wait X seconds for cmd prompt after login power_timeout: Test X seconds for status change after ON/OFF delay: Wait X seconds before fencing is started ipmitool_path: Path to ipmitool binary shell_timeout: Wait X seconds for cmd prompt after issuing command retry_on: Count of attempts to retry power on sudo: Use sudo (without password) when calling 3rd party sotfware. stonith-timeout: How long to wait for the STONITH action (reboot, on, off) to complete per a stonith device. priority: The priority of the stonith resource. Devices are tried in order of highest priority to lowest. pcmk_host_map: A mapping of host names to ports numbers for devices that do not support host names. pcmk_host_list: A list of machines controlled by this device (Optional unless pcmk_host_check=static-list). pcmk_host_check: How to determine which machines are controlled by the device. ---- Step 5: `pcs cluster cib stonith_cfg` Step 6: Here are example parameters for creating our STONITH resource: ---- [root@pcmk-1 ~]# pcs -f stonith_cfg stonith create ipmi-fencing fence_ipmilan \ pcmk_host_list="pcmk-1 pcmk-2" ipaddr=10.0.0.1 login=testuser \ passwd=acd123 op monitor interval=60s [root@pcmk-1 ~]# pcs -f stonith_cfg stonith ipmi-fencing (stonith:fence_ipmilan): Stopped ---- Steps 7-10: Enable STONITH in the cluster: ---- [root@pcmk-1 ~]# pcs -f stonith_cfg property set stonith-enabled=true [root@pcmk-1 ~]# pcs -f stonith_cfg property Cluster Properties: cluster-infrastructure: corosync cluster-name: mycluster dc-version: 1.1.12-a14efad have-watchdog: false stonith-enabled: true ---- Step 11: `pcs cluster cib-push stonith_cfg` Step 12: Test: ---- [root@pcmk-1 ~]# pcs cluster stop pcmk-2 [root@pcmk-1 ~]# stonith_admin --reboot pcmk-2 ---- After a successful test, login to any rebooted nodes, and start the cluster (with `pcs cluster start`).