Managing Serviceguard Eighteenth Edition, September 2010

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 289) and failover_policy (page 292) 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 289) 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 294),
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.
• If pkg1 is a failover package and pkg2 is a multi-node or system multi-node
package, and pkg2 fails, pkg1 will halt and fail over to the next node on its
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
180 Planning and Documenting an HA Cluster