Managing HP Serviceguard for Linux Ninth Edition, April 2009

node_name list on which pkg2 is running (and any other dependencies, such as
resource dependencies or a dependency on a third package, are met).
• In the case of failover packages with a configured_node failover_policy, a set of
rules governs under what circumstances pkg1 can force pkg2 to start on a given
node. This is called dragging and is determined by each package’s priority (page 201).
See “Dragging Rules for Simple Dependencies” (page 123).
• If pkg2 fails, Serviceguard will halt pkg1 and any other packages that depend
directly or indirectly on pkg2.
By default, Serviceguard halts packages in dependency order, the dependent
package(s) first, then the package depended on. In our example, pkg1 would be
halted first, then pkg2. If there were a third package, pkg3, that depended on
pkg1, pkg3 would be halted first, then pkg1, then pkg2.
If the halt script for any dependent package hangs, by default the package depended
on will wait forever (pkg2 will wait forever for pkg1, and if there is apkg3 that
depends on pkg1, pkg1 will wait forever for pkg3). You can modify this behavior
by means of the successor_halt_timeout parameter (page 200)). (The successor of a
package depends 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 201) 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 201) is configured_node. Assume pkg1 depends on pkg2, that
node1, node2 and node3 are all specified (in some order) under node_name (page 197)
in the configuration file for each package, and that failback_policy (page 201) is set to
automatic for each package.
Package Configuration Planning 123