Managing Serviceguard Sixteenth Edition, March 2009

Serviceguard provides two ways to do this: you can use the preview mode of
Serviceguard commands, or you can use the cmeval (1m) command to simulate
different cluster states.
Alternatively, you might want to model changes to the cluster as a whole; cmeval
allows you to do this; see “Using cmeval” (page 326).
What You Can Preview
You can preview any of the following, or all of them simultaneously:
• Cluster bring-up (cmruncl)
• Cluster node state changes (cmrunnode, cmhaltnode)
• Package state changes (cmrunpkg, cmhaltpkg)
• Package movement from one node to another
• Package switching changes (cmmodpkg -e)
• Availability of package subnets, EMS resources, and storage
• Changes in package priority, node order, dependency, failover and failback policy,
node capacity and package weight
Using Preview mode for Commands and in Serviceguard Manager
The following commands support the -t option, which allows you to run the command
in preview mode:
• cmhaltnode [–t] [–f] <node_name>
• cmrunnode [–t] <node_name>
• cmhaltpkg [–t] <package_name>
• cmrunpkg [–t] [-n node_name] <package_name>
• cmmodpkg { -e [-t] | -d } [-n node_name] <package_name>
• cmruncl –v [–t]
NOTE: You cannot use the -t option with any command operating on a package in
maintenance mode; see “Maintaining a Package: Partial-Startup Maintenance Mode”
(page 319).
For more information about these commands, see their respective manpages. You can
also perform these preview functions in Serviceguard Manager: check the Preview
[...] box for the action in question.
When you use the -t option, the command, rather than executing as usual, predicts
the results that would occur, sending a summary to $stdout. For example, assume
that pkg1 is a high-priority package whose primary node is node1, and which depends
on pkg2 and pkg3 to run on the same node. These are lower-priority packages which
are currently running on node2. pkg1 is down and disabled, and you want to see the
effect of enabling it:
Reconfiguring a Cluster 325