Managing HP Serviceguard for Linux Ninth Edition, April 2009

by a master control script that is installed with Serviceguard; see Chapter 6:
“Configuring Packages and Their Services ” (page 189), for instructions for creating
modular packages.
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 auto_run parameter is set in the package configuration file.
A package switch normally 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.
NOTE: It is possible to configure a cluster that spans subnets joined by a router, with
some nodes using one subnet and some another. This is known as a cross-subnet
configuration. In this context, you can configure packages to fail over from a node on
one subnet to a node on another, and you will need to configure a relocatable IP address
for each subnet the package is configured to start on; see “About Cross-Subnet Failover”
(page 141), and in particular the subsection “Implications for Application Deployment”
(page 142).
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, normally all of them must be available on the target
node before the package will be started. (In a cross-subnet configuration, all the
monitored subnets that are specified for this package, and configured on the target
node, must be up.)
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.
How the Package Manager Works 51