Figure 2 Typical Cluster After Failover

After this transfer, the failover package typically remains on the adoptive node as long the adoptive node continues running. If you wish, however, you can configure the package to return to its primary node as soon as the primary node comes back online. Alternatively, you may manually transfer control of the package back to the primary node at the appropriate time.

Figure 2 does not show the power connections to the cluster, but these are important as well. In order to remove all single points of failure from the cluster, you should provide as many separate power circuits as needed to prevent a single point of failure of your nodes, disks and disk mirrors. Each power circuit should be protected by an uninterruptible power source. For more details, refer to the section on “Power Supply Planning” in Chapter 4, “Planning and Documenting an HA Cluster.”

Serviceguard is designed to work in conjunction with other high availability products, such as:

Mirrordisk/UX or Veritas Volume Manager, which provide disk redundancy to eliminate single points of failure in the disk subsystem;

System Fault Management (SFM), which lets you monitor and detect failures that are not directly handled by Serviceguard and influences the availability of packages based on availability of resources;

Event Monitoring Service (EMS), which lets you monitor and detect failures that are not directly handled by Serviceguard;

disk arrays, which use various RAID levels for data protection;

HP-supported uninterruptible power supplies (UPS), such as HP PowerTrust, which eliminates failures related to power outage.

HP recommends these products; in conjunction with Serviceguard they provide the highest degree of availability.

About Veritas CFS and CVM from Symantec

Check the Serviceguard/SGeRAC/SMS/Serviceguard Manager Plug-in Compatibility and Feature Matrix and the latest Release Notes for your version of Serviceguard for up-to-date information about support for Veritas Cluster File System (CFS) and Cluster Volume Manager (CVM): http:// www.hp.com/go/hpux-serviceguard-docs.

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HP Serviceguard manual About Veritas CFS and CVM from Symantec, Typical Cluster After Failover