HP B6960-96035 User Manual download pdf (Page 81)

you can make an appropriate determination of the ownership of the package

(MC/SG, Veritas Cluster) or group (MSCS).

What is a package or group?

A package (MC/SG, Veritas Cluster) or a group (MSCS) is a collection of resources

that are needed to run a specific cluster-aware application. Each cluster-aware

application declares its own critical resources. The following resources must be

defined in each group or package:

• Shared disk volumes (MSCS, Novell NetWare Cluster Services)

• Shared volume groups (MC/SG, Veritas Cluster)

• Network IP names

• Network IP addresses

• Cluster-aware application services

What is a virtual server?

Disk volumes and volume groups represent shared physical disks. A network IP name

and a network IP address are resources that define a virtual server of a cluster-aware

application. Its IP name and address are cached by the cluster software and mapped

to the cluster node where the specific package or group is currently running. Since

the group or package can switch from one node to another, the virtual server can

reside on different machines in different time frames.

What is a failover?

Each package or group has its own “preferred” node where it normally runs. Such

a node is called a primary node. A package or group can be moved to another

cluster node (one of the secondary nodes). The process of transferring a package or

group from the primary cluster node to the secondary is called failover or switchover.

The secondary node accepts the package or group in case of failure of the primary

node. A failover can occur for many different reasons:

• Software failures on the primary node

• Hardware failures on the primary node

• The administrator intentionally transfers the ownership because of maintenance

on the primary node

In a cluster environment there can be more than one secondary node but only one

can be the primary.

Concepts guide 81

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HP B6960-96035 User Manual Page 81