Managing HP Serviceguard for Linux, Sixth Edition, August 2006

Understanding Serviceguard Software Components
How Package Control Scripts Work
Chapter 3 59
Before the Control Script Starts
First, a node is selected. This node must be in the package’s node list, it
must conform to the package’s failover policy, and any resources required
by the package must be available on the chosen node. One resource is the
subnet that is monitored for the package. If the subnet is not available,
the package cannot start on this node. Another type of resource is a
dependency on a monitored external resource. If monitoring shows a
value for a configured resource that is outside the permitted range, the
package cannot start.
Once a node is selected, a check is then done to make sure the node
allows the package to start on it. Then services are started up for a
package by the control script on the selected node. Strictly speaking, the
run script on the selected node is used to start the package.
During Run Script Execution
Once the package manager has determined that the package can start on
a particular node, it launches the run script (that is, the control script
executed with the ‘start’ parameter. This script carries out the following
steps (also shown in Figure 3-15):
1. Activates volume groups.
2. Mounts file systems.
3. Assigns package IP addresses to the LAN card on the node.
4. Executes any customer-defined run commands.
5. Starts each package service.