Managing HP Serviceguard for Linux, Seventh Edition, July 2007

Planning and Documenting an HA Cluster
Package Configuration Planning
Chapter 4116
Make a package dependent on another package if the first package
cannot (or should not) function without the services provided by the
second. For example, pkg1 might run a real-time web interface to a
database managed by pkg2. In this case it might make sense to make
pkg1 dependent on pkg2.
In considering whether or not to create a dependency between packages,
consider the Rules and Guidelines that follow.
Rules
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 (see page 202) and failover_policy (see
page 205) 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 list (see node_name, page 202) must contain all of the
nodes on pkg1’s.