Installation guide

The service would need four nfsclient resources — one per file system (a total of two for file

systems), and one per target machine (a total of two for target machines).

The service would need to specify export path and file system ID to each nfsclient, which

introduces chances for errors in the configuration.

In Example C.5, “ NFS Service Set Up for Resource Reuse and Inheritance” however, the NFS client

resources nfsclient:bob and nfsclient:jim are defined once; likewise, the NFS export resource

nfsexport:exports is defined once. All the attributes needed by the resources are inherited from parent

resources. Because the inherited attributes are dynamic (and do not conflict with one another), it is

possible to reuse those resources — which is why they are defined in the resources block. It may not

be practical to configure some resources in multiple places. For example, configuring a file system

resource in multiple places can result in mounting one file system on two nodes, therefore causing

problems.

C.4 . Failure Recovery and Independent Subt rees

In most enterprise environments, the normal course of action for failure recovery of a service is to

restart the entire service if any component in the service fails. For example, in Example C.6, “ Service

foo Normal Failure Recovery”, if any of the scripts defined in this service fail, the normal course of

action is to restart (or relocate or disable, according to the service recovery policy) the service.

However, in some circumstances certain parts of a service may be considered non-critical; it may be

necessary to restart only part of the service in place before attempting normal recovery. To

accomplish that, you can use the __independent_subtree attribute. For example, in

Example C.7, “ Service foo Failure Recovery with __independent_subtree Attribute” , the

__independent_subtree attribute is used to accomplish the following actions:

If script:script_one fails, restart script:script_one, script:script_two, and script:script_three.

If script:script_two fails, restart just script:script_two.

If script:script_three fails, restart script:script_one, script:script_two, and script:script_three.

If script:script_four fails, restart the whole service.

Examp le C.6 . Service foo No rmal Failu re Reco very

</script>

</service>

Examp le C.7. Service foo Failu re R eco very wit h __independent_subtree At t rib u t e

</script>

</service>

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