Managing HP Serviceguard A.11.20.10 for Linux, December 2012

Table 11 Types of Changes to the Cluster Configuration (continued)
Required Cluster StateChange to the Cluster Configuration
Must delete the interface from the cluster configuration,
reconfigure it, then add it back into the cluster configuration.
See “What You Must Keep in Mind” (page 221). Cluster can be
running throughout.
Reconfigure IP addresses for a NIC used by the cluster
Cluster can be running.Change NETWORK_POLLING_INTERVAL
Cluster can be running. See the entries for these parameters
under “Cluster Configuration Parameters ” (page 86)for more
information.
Change IP Monitor parameters: SUBNET,
IP_MONITOR, POLLING TARGET
Cluster can be running.Change MEMBER_TIMEOUT and
AUTO_START_TIMEOUT
Cluster and package can be running.Change Access Control Policy
Node(s) associated with the corresponding SITE or
SITE_NAME entry must be down. When the cluster is running
you cannot add SITE or SITE_NAME entries.
Change SITE, SITE_NAME
7.6.1 Previewing the Effect of Cluster Changes
Many variables affect package placement, including the availability of cluster nodes; the availability
of networks and other resources on those nodes; failover and failback policies; and package
weights, dependencies, and priorities, if you have configured them. You can preview the effect
on packages of certain actions or events before they actually occur.
For example, you might want to check to see if the packages are placed as you expect when the
cluster first comes up; or preview what happens to the packages running on a given node if the
node halts, or if the node is then restarted; or you might want to see the effect on other packages
if another, currently disabled, package is enabled, or if a package halts and cannot restart because
none of the nodes on its node_list is available.
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 218).
7.6.1.1 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, resources, and storage
• Changes in package priority, node order, dependency, failover and failback policy, node
capacity and package weight
7.6.1.2 Using Preview mode for Commands in Serviceguard Manager
The following commands support the -t option, which allows you to run the command in preview
mode:
7.6 Reconfiguring a Cluster 217