Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Understanding Serviceguard Software Components
How the Package Manager Works
Chapter 352
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” on page 136,
and in particular the subsection “Implications for Application
Deployment” on page 137.
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