Managing Serviceguard 13th Edition, February 2007

Understanding Serviceguard Software Components
How Package Control Scripts Work
Chapter 392
7. When the node fails
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 or on a special-purpose
package. 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
This section applies only to failover packages.
Once the package manager has determined that the package can start on
a particular node, it launches the run script (that is, a failover package’s
control script that is executed with the ‘start’ parameter). This failover
package script carries out the following steps (also shown in
Figure 3-14):
1. Activates volume groups or disk 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.
6. Starts up any EMS (Event Monitoring Service) resources needed by
the package that were specially marked for deferred startup.
7. Exits with an exit code of zero (0).