Managing Serviceguard Sixteenth Edition, March 2009

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 263) and failover_policy (page 266) 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 263) must contain all of the nodes on pkg1’s.
— 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 268),
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
node. This is called dragging and is determined by each package’s priority (page 267).
See “Dragging Rules for Simple Dependencies” (page 168).
• 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
Package Configuration Planning 167