Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Planning and Documenting an HA Cluster
Package Configuration Planning
Chapter 4126
NOTE This applies only when the packages are automatically started (package
switching enabled); cmrunpkg will never force a package to halt.
Keep in mind that you do not have to set priority, even when one or
more packages depend on another. The default value, no_priority, may
often result in the behavior you want. For example, if pkg1 depends on
pkg2, and priority is set to no_priority for both packages, and other
parameters such as node_name and auto_run are set as recommended in
this section, then pkg1 will normally follow pkg2 to wherever both can
run, and this is the common-sense (and may be the most desirable)
outcome.
The following examples express the rules as they apply to two failover
packages whose failover_policy (see page 214) is configured_node.
Assume pkg1 depends on pkg2, that node1, node2 and node3 are all
specified (in some order) under node_name (see page 210) in the
configuration file for each package, and that failback_policy (see
page 214) is set to automatic for each package.
NOTE Keep the following in mind when reading the examples that follow, and
when actually configuring priorities:
1. auto_run (see page 211) should be set to yes for all the packages
involved; the examples assume that it is.
2. Priorities express a ranking order, so a lower number means a higher
priority (10 is a higher priority than 30, for example).
HP recommends assigning values in increments of 20 so as to leave
gaps in the sequence; otherwise you may have to shuffle all the
existing priorities when assigning priority to a new package.
no_priority, the default, is treated as a lower priority than any
numerical value.
3. All packages with no_priority are by definition of equal priority,
and there is no other way to assign equal priorities; a numerical
priority must be unique within the cluster. See priority (page 215)
for more information.