Jump to content United States-English
HP.com Home Products and Services Support and Drivers Solutions How to Buy
» Contact HP
More options
HP.com home
Managing Serviceguard Fifteenth Edition > Chapter 2 Understanding Serviceguard Hardware Configurations

Redundancy of Cluster Components


Technical documentation

Complete book in PDF
» Feedback
Content starts here

 » Table of Contents

 » Index

In order to provide a high level of availability, a typical cluster uses redundant system components, for example two or more SPUs and two or more independent disks. This redundancy eliminates single points of failure. In general, the more redundancy, the greater your access to applications, data, and supportive services in the event of a failure.

In addition to hardware redundancy, you must have the software support which enables and controls the transfer of your applications to another SPU or network after a failure. Serviceguard provides this support as follows:

  • In the case of LAN failure, Serviceguard switches to a standby LAN or moves affected packages to a standby node.

  • In the case of SPU failure, your application is transferred from a failed SPU to a functioning SPU automatically and in a minimal amount of time.

  • For failure of other monitored resources, such as disk interfaces, a package can be moved to another node.

  • For software failures, an application can be restarted on the same node or another node with minimum disruption.

Serviceguard also gives you the advantage of easily transferring control of your application to another SPU in order to bring the original SPU down for system administration, maintenance, or version upgrades.

The current maximum number of nodes supported in a Serviceguard cluster is 16. SCSI disks or disk arrays can be connected to a maximum of 4 nodes at a time on a shared (multi-initiator) bus. Disk arrays using fibre channel and those that do not use a shared bus — such as the HP StorageWorks XP Series and the EMC Symmetrix — can be simultaneously connected to all 16 nodes.

The guidelines for package failover depend on the type of disk technology in the cluster. For example, a package that accesses data on a SCSI disk or disk array can failover to a maximum of 4 nodes. A package that accesses data from a disk in a cluster using Fibre Channel or HP StorageWorks XP or EMC Symmetrix disk technology can be configured for failover among 16 nodes.

Note that a package that does not access data from a disk on a shared bus can be configured to fail over to as many nodes as you have configured in the cluster (regardless of disk technology). For instance, if a package only runs local executables, it can be configured to failover to all nodes in the cluster that have local copies of those executables, regardless of the type of disk connectivity.

Printable version
Privacy statement Using this site means you accept its terms Feedback to webmaster
© Hewlett-Packard Development Company, L.P.