VERITAS Volume Manager 3.1 Administrator's Guide

Cluster Functionality
Cluster Functionality Overview
Chapter 7300
Figure 7-1 Example of a 4-Node Cluster
The system administrator designates a disk group as cluster-shareable
using the vxdg utility (see “vxdg Utility” for more information). Once a
disk group is imported as cluster-shareable for one node, the disk
headers are marked with the cluster ID. When other nodes join the
cluster, they will recognize the disk group as being cluster-shareable and
import it. The system administrator can import or deport a shared disk
group at any time; the operation takes places in a distributed fashion on
all nodes.
Each physical disk is marked with a unique disk ID. When the cluster
starts up on the master, it imports all the shared disk groups (except for
any that have the noautoimport attribute set). When a slave tries to
join, the master sends it a list of the disk IDs it has imported and the
slave checks to see if it can access all of them. If the slave cannot access
one of the imported disks on the list, it abandons its attempt to join the
cluster. If it can access all of the disks on the list, it imports the same set
of shared disk groups as the master and joins the cluster. When a node
leaves the cluster, it deports all its imported shared disk groups, but they
remain imported on the surviving nodes.
Cluster-shareable
Disks
Node 1
Network
(master)
Cluster-shareable
Disk Group
Node 2
(slave)
Node 3
(slave)
Node 4
(slave)