Chapter

13

Administering cluster functionality

A cluster consists of a number of hosts or nodes that share a set of disks. The main benefits of cluster configurations are:

Availability

If one node fails, the other nodes can still access the shared

 

disks. When configured with suitable software, mission-critical

 

applications can continue running by transferring their

 

execution to a standby node in the cluster. This ability to provide

 

continuous uninterrupted service by switching to redundant

 

hardware is commonly termed failover.

 

Failover is transparent to users and high-level applications for

 

database and file-sharing. You must configure cluster

 

management software, such as Veritas Cluster Server (VCS), to

 

monitor systems and services, and to restart applications on

 

another node in the event of either hardware or software failure.

 

VCS also allows you to perform general administration tasks

 

such as making nodes join or leave a cluster.

 

Note that a standby node need not remain idle. It could be used

 

to serve other applications in parallel.

Off-host processing

Clusters can reduce contention for system resources by

 

performing activities such as backup, decision support and

 

report generation on the more lightly loaded nodes of the

 

cluster. This allows businesses to derive enhanced value from

 

their investment in cluster systems.

The cluster functionality of Veritas Volume Manager (CVM) allows up to 16 nodes in a cluster to simultaneously access and manage a set of disks under VxVM control (VM disks). The same logical view of disk configuration and any changes to this is available on all the nodes. When the cluster functionality is

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HP Veritas Volume Manager 5.0 -UX 11i v3 manual Administering cluster functionality