Managing HP Serviceguard for Linux, Seventh Edition, July 2007

Understanding Serviceguard Software Components
How the Package Manager Works
Chapter 348
Deciding When and Where to Run and Halt Failover Packages
The package configuration file assigns a name to the package and
includes a list of the nodes on which the package can run.
Failover packages list the nodes in order of priority (i.e., the first node in
the list is the highest priority node). In addition, failover packages’ files
contain three parameters that determine failover behavior. These are the
auto_run parameter, the failover_policy parameter, and the
failback_policy parameter.
Failover Packages’ Switching Behavior The auto_run parameter
(known in earlier versions of Serviceguard as the
PKG_SWITCHING_ENABLED parameter) defines the default global
switching attribute for a failover package at cluster startup: that is,
whether Serviceguard can automatically start the package when the
cluster is started, and whether Serviceguard should automatically
restart the package on a new node in response to a failure. Once the
cluster is running, the package switching attribute of each package can
be temporarily set with the cmmodpkg command; at reboot, the
configured value will be restored.
The parameter is set in the package configuration file.
A package switch involves moving failover packages and their associated
IP addresses to a new system. The new system must already have the
same subnet configured and working properly, otherwise the packages
will not be started.
When a package fails over, TCP connections are lost. TCP applications
must reconnect to regain connectivity; this is not handled automatically.
Note that if the package is dependent on multiple subnets, all of them
must be available on the target node before the package will be started.
If the package has a dependency on a resource or another package, the
dependency must be met on the target node before the package can start.
The switching of relocatable IP addresses is shown in Figure 3-6 and
Figure 3-7. Figure 3-6 shows a two node cluster in its original state with
Package 1 running on Node 1 and Package 2 running on Node 2. Users
connect to node with the IP address of the package they wish to use.
Each node has a stationary IP address associated with it, and each
package has an IP address associated with it.