Managing Serviceguard Seventeenth Edition, First Reprint December 2009

Make a package dependent on another package if the first package cannot (or should
not) function without the services provided by the second, on the same node. For
example, pkg1 might run a real-time web interface to a database managed by pkg2
on the same node. In this case it might make sense to make pkg1 dependent on pkg2.
In considering whether or not to create a simple dependency between packages, use
the Rules for Simple Dependencies and Guidelines for Simple Dependencies that follow.
Rules for Simple Dependencies
Assume that we want to make pkg1 depend on pkg2.
NOTE: pkg1 can depend on more than one other package, and pkg2 can depend on
another package or packages; we are assuming only two packages in order to make
the rules as clear as possible.
• pkg1 will not start on any node unless pkg2 is running on that node.
• pkg1’s package_type (page 265) and failover_policy (page 268) constrain the type and
characteristics of pkg2, as follows:
— If pkg1 is a multi-node package, pkg2 must be a multi-node or system
multi-node package. (Note that system multi-node packages are not supported
for general use.)
— If pkg1 is a failover package and its failover_policy is min_package_node,
pkg2 must be a multi-node or system multi-node package.
— If pkg1 is a failover package and its failover_policy is configured_node, pkg2
must be:
◦ a multi-node or system multi-node package, or
◦ a failover package whose failover_policy is configured_node.
• pkg2 cannot be a failover package whose failover_policy is min_package_node.
• pkg2’s node node_name list (page 265) must contain all of the nodes on pkg1’s.
— This means that if pkg1 is configured to run on any node in the cluster (*),
pkg2 must also be configured to run on any node.
NOTE: If pkg1 lists all the nodes, rather than using the asterisk (*), pkg2
must also list them.
— Preferably the nodes should be listed in the same order if the dependency is
between packages whose failover_policy is configured_node; cmcheckconf
and cmapplyconf will warn you if they are not.
• A package cannot depend on itself, directly or indirectly.
That is, not only must pkg1 not specify itself in the dependency_condition (page 270),
but pkg1 must not specify a dependency on pkg2 if pkg2 depends on pkg1, or
if pkg2 depends on pkg3 which depends on pkg1, etc.
Package Configuration Planning 169