HP manual What You Can Preview, Using Preview mode for Commands and in Serviceguard Manager

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 -toption, 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 -toption with any command operating on a package in maintenance

mode; see “Maintaining a Package: Maintenance Mode” (page 287).

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 -toption, 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:

cmmodpkg -e -t pkg1

You will see output something like this:

package:pkg3node:node2action:failing

package:pkg2node:node2action:failing

package:pkg2node:node1action:starting

package:pkg3node:node1action:starting

package:pkg1node:node1action:starting cmmodpkg: Command preview completed successfully

This shows that pkg1, when enabled, will “drag” pkg2 and pkg3 to its primary node, node1. It can do this because of its higher priority; see “Dragging Rules for Simple Dependencies” (page 139). Running the preview confirms that all three packages will successfully start on node2 (assuming conditions do not change between now and when you actually enable pkg1, and there are no failures in the run scripts).

Reconfiguring a Cluster 293