Managing Serviceguard 12th Edition, March 2006

Serviceguard at a Glance
What is Serviceguard?
Chapter 122
What is Serviceguard?
Serviceguard allows you to create high availability clusters of HP 9000 or
HP Integrity servers. A high availability computer system allows
application services to continue in spite of a hardware or software
failure. Highly available systems protect users from software failures as
well as from failure of a system processing unit (SPU), disk, or local area
network (LAN) component. In the event that one component fails, the
redundant component takes over. Serviceguard and other high
availability subsystems coordinate the transfer between components.
A Serviceguard cluster is a networked grouping of HP 9000 or HP
Integrity servers (host systems known as nodes) having sufficient
redundancy of software and hardware that a single point of failure
will not significantly disrupt service.
A package groups application services (individual HP-UX processes)
together. There are failover packages, system multi-node packages, and
multi-node packages:
The typical high availablity package is a failover package. It
usually is configured to run on several nodes in the cluster, and runs
on one at a time. If a service, node, network, or other package
resource fails on the node where it is running, Serviceguard can
automatically transfer control of the package to another cluster node,
allowing services to remain available with minimal interruption.
There are also packages that run on several cluster nodes at once,
and do not fail over. These are called system multi-node packages
and multi-node packages. At the release of Serviceguard A.11.17,
the only non-failover packages that are supported are the ones
specified by Hewlett-Packard, for example the packages HP supplies
for use with the VERITAS Cluster Volume Manager and the
VERITAS Cluster File System.
A system multi-node package must run on all nodes that are active
in the cluster. If it fails on one active node, that node halts. A
multi-node package can be configured to run on one or more cluster
nodes. It is considered UP as long as it is running on any of its
configured nodes.