Managing HP Serviceguard A.11.20.10 for Linux, December 2012

1. Use cmviewcl -v -f line to write the current cluster configuration out to a file.
2. Edit the file to include the events or changes you want to preview
3. Using the file from Step 2 as input, run cmeval to preview the results of the changes.
For example, assume that pkg1 is a high-priority package whose primary node is node1, and
which depends on pkg2 and pkg3 to be running on the same node. These lower-priority-packages
are currently running on node2. pkg1 is down and disabled, and you want to see the effect of
enabling it.
In the output of cmviewcl -v -f line, you would find the line
package:pkg1|autorun=disabled and change it to package:pkg1|autorun=enabled.
You should also make sure that the nodes the package is configured to run on are shown as
available; for example: package:pkg1|node:node1|available=yes. Then save the file (for
example, as newstate.in) and run cmeval:
cmeval -v newstate.in
You would see output something like this:
package:pkg3|node:node2|action:failing
package:pkg2|node:node2|action:failing
package:pkg2|node:node1|action:starting
package:pkg3|node:node1|action:starting
package:pkg1|node:node1|action:starting
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 109).
Running cmeval 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.)
NOTE: cmeval cannot predict run and halt script failures.
This is a simple example; you can use cmeval for much more complex scenarios; see “What You
Can Preview” (page 217).
IMPORTANT: For detailed information and examples, see the cmeval (1m) manpage.
7.6.2 Reconfiguring a Halted Cluster
You can make a permanent change in cluster configuration when the cluster is halted. This procedure
must be used for changes marked “Cluster must not be running” in Table 11, but it can be used
for any other cluster configuration changes as well.
Use the following steps:
1. Halt the cluster on all nodes.
2. On one node, reconfigure the cluster as described in “Building an HA Cluster Configuration”
(page 129). You can use cmgetconf to generate a template file, which you then edit.
3. Make sure that all nodes listed in the cluster configuration file are powered up and accessible.
Use cmapplyconf to copy the binary cluster configuration file to all nodes. This file overwrites
any previous version of the binary cluster configuration file.
4. Use cmruncl to start the cluster on all nodes, or on a subset of nodes.
7.6.3 Reconfiguring a Running Cluster
You can add new nodes to the cluster configuration or delete nodes from the cluster configuration
while the cluster is up and running. Note the following, however:
• You cannot remove an active node from the cluster. You must halt the node first.
• The only configuration change allowed while a node is unreachable (for example, completely
disconnected from the network) is to delete the unreachable node from the cluster configuration.
7.6 Reconfiguring a Cluster 219