Managing HP Serviceguard A.11.20.20 for Linux, May 2013

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.
3.3.1.2.3 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 130), and in particular the subsection “Implications
for Application Deployment” (page 131).
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.
The switching of relocatable IP addresses is shown in the figures that follow. Users connect to each
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.
3.3 How the Package Manager Works 45