HP Serviceguard A.11.20- Managing Serviceguard Twentieth Edition, August 2011

on that package; in our example, pkg1 is a successor of pkg2; conversely pkg2 can be
referred to as a predecessor of pkg1.)
Dragging Rules for Simple Dependencies
The priority parameter (page 238) gives you a way to influence the startup, failover, and failback
behavior of a set of failover packages that have a configured_node failover_policy,
when one or more of those packages depend on another or others.
The broad rule is that a higher-priority package can drag a lower-priority package, forcing it to
start on, or move to, a node that suits the higher-priority package.
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 (page 237) is configured_node. Assume pkg1 depends on pkg2, that
node1, node2 and node3 are all specified (not necessarily in that order) under node_name
(page 235) in the configuration file for each package, and that failback_policy (page 238) is
set to automatic for each package.
Package Configuration Planning 139