Installation guide

Cluster Service Resource Check and Failover Timeout

This appendix describes how rg manager monitors the status of cluster resources, and how to

modify the status check interval. The appendix also describes the __enfo rce_ti meo uts service

parameter, which indicates that a timeout for an operation should cause a service to fail.

Note

To fully comprehend the information in this appendix, you may require detailed understanding

of resource agents and the cluster configuration file, /etc/cl uster/cl uster. co nf. For a

comprehensive list and description of cl uster. co nf elements and attributes, refer to the

cluster schema at /usr/share/cl uster/cluster. rng , and the annotated schema at

/usr/share/d o c/cman-X. Y . ZZ/cl uster_co nf. html (for example

/usr/share/d o c/cman-3. 0 . 12/cluster_conf. html ).

D.1. Modifying t he Resource St at us Check Int erval

rg manager checks the status of individual resources, not whole services. Every 10 seconds,

rgmanager scans the resource tree, looking for resources that have passed their "status check"

interval.

Each resource agent specifies the amount of time between periodic status checks. Each resource

utilizes these timeout values unless explicitly overridden in the cl uster. co nf file using the special

<actio n> tag:

This tag is a special child of the resource itself in the cl uster. co nf file. For example, if you had a

file system resource for which you wanted to override the status check interval you could specify the

file system resource in the cl uster.co nf file as follows:

<nfsexport...>

</nfsexport>

</fs>

Some agents provide multiple "depths" of checking. For example, a normal file system status check

(depth 0) checks whether the file system is mounted in the correct place. A more intensive check is

depth 10, which checks whether you can read a file from the file system. A status check of depth 20

checks whether you can write to the file system. In the example given here, the d epth is set to *,

which indicates that these values should be used for all depths. The result is that the test file system

is checked at the highest-defined depth provided by the resource-agent (in this case, 20) every 10

seconds.

D.2. Enforcing Resource T imeout s

There is no timeout for starting, stopping, or failing over resources. Some resources take an

indeterminately long amount of time to start or stop. Unfortunately, a failure to stop (including a

timeout) renders the service inoperable (failed state). You can, if desired, turn on timeout enforcement

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