HP B6960-96035, Concepts Manual

Page: 81 / 422

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.
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