Managing Serviceguard 14th Edition, June 2007

Serviceguard at a Glance
What is Serviceguard?
Chapter 126
What is Serviceguard?
Serviceguard allows you to create high availability clusters of HP 9000 or
HP Integrity servers (or a mixture of both; see the release notes for your
version for details and restrictions).
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 (or both), 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 availability 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. Examples are the packages HP supplies
for use with the Veritas Cluster Volume Manager and Veritas Cluster
File System from Symantec (on HP-UX releases that support them;
see “About Veritas CFS and CVM from Symantec” on page 29).
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. System
multi-node packages are supported only for HP-supplied
applications.