Setting Up High Availability Through YaST
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That being said, let's begin!
The HA component in YaST is accessed as a subcomponent in the System tools.
The HA wizard begins with the configuration of Heartbeat.
Starting the Heartbeat server when booting is the desired method. As a side-note, starting it now (for the first time) will return an unspecified error because Heartbeat is really unconfigured as of yet.
Configuring the node list is the next step. In it's current development, HA will only handle a two-node list. The/etc/hostsfile on both nodes should include the partner node to avoid any name resolution issue. Also, the names should match the output of uname -n on each node.
Media configuration is the next step. This step configures the method/media Heartbeat will use to communicate from node to node. It is highly suggested to configure more than one media for redundancy. When configuring this, select the medium and specifics, then click on the [Add] button to add it to the list.
If only one media of communication is configured, an error will be generated.
Suffice it to say, after configuring the media through which to communicate, Heartbeat then requires an Authentication Method. This authentication method is not for authentication to the nodes, but for verification of the Heartbeat messages. As stated, bothmd5and sha1 require a shared secret. It is recommended to choose the sha1 method, which is the strongest authentication scheme available.
Resource configuration is, then, the next step. This configuration must be the same on both nodes. Resources are just scripts that are used to properly stop and start services. Some sample scripts are included in the/etc/ha.d/resource.ddirectory and many are available online.
NOTE: If using a service that requires shared media, pay particular attention to the DRBD configuration and requirements in the scripts. NFS, SAMBA, and other file access services will require this. Configuration of DRBD is outside the scope of this document.
For failback, there are three modes: Legacy, On, and Off. If Automatic Failback is set to on, Heartbeat migrates resources back to the primary owner as soon as it becomes available again. This automatically restores the balancing of resources between the nodes, but requires that the resources are briefly stopped so they can be cleanly started, leading to a minor interruption of service. For most scenarios, off is the correct choice. It requires the administrator to trigger the failback of resources manually (using the hb_standby command line tool) as soon as the failure is resolved. This allows scheduling of a maintenance window to eliminate interruption of the service even more. Legacy is the old default for compatibility with former Heartbeat releases. It activates the automatic failback if not all nodes support the new directive. Explicitly choosing either on or off is recommended for new deployments.
The configuration of STONITH (Shoot The Other Node In The Head) is the next step. To protect the shared data, STONITH must be configured. Heartbeat is capable of driving a number of serial and network power switches to prevent a potentially faulty node from corrupting the shared data. It needs to know which node can access the power switch.
The STONITH Type must match the module name capable of controlling the power switch used. The Parameters are also specific to the module. See the stonith -h command line tool for a listing of the supported modules and the parameters they accept.
That's pretty much it. If you haven't already, runrcheartbeat startas the root user, and your resource should come online.
For troubleshooting, pay particular attention to any output provided by the rcheartbeat status or rcheartbeat start. If heartbeat starts successfully, but the resource doesn't come online, then further troubleshooting of the resource script should be performed.
There are additonal options that can be configured such as Time-outs, IP Fail and Ping Groups. These, however are outside the scope of this basic documentation. To access these parameters, re-run the Heartbeat module in YaST and select the desired module from the tree list..
Formerly known as TID# 10098672
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- Document ID:3154995
- Creation Date:02-MAR-07
- Modified Date:15-JAN-18
- SUSESUSE Linux Enterprise Server
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