Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Figure 6-1 shows a 2-node cluster with node 0, a fibre channel switch and disk
enclosure enc0 in building A, and node 1, another switch and enclosure enc1 in
building B.
Figure 6-1
Typical arrangement of a 2-node campus cluster
Fibre Channel switches
Disk enclosures
enc1enc0
Node 0
Redundant private
network
Node 1
Building A Building B
The fibre channel connectivity is multiply redundant to implement redundant-loop
access between each node and each enclosure. As usual, the two nodes are also
linked by a redundant private network.
A serial split brain condition typically arises in a cluster when a private
(non-shared) disk group is imported on Node 0 with Node 1 configured as the
failover node.
If the network connections between the nodes are severed, both nodes think that
the other node has died. (This is the usual cause of the split brain condition in
clusters). If a disk group is spread across both enclosure enc0 and enc1, each
portion loses connectivity to the other portion of the disk group. Node 0 continues
to update to the disks in the portion of the disk group that it can access. Node 1,
operating as the failover node, imports the other portion of the disk group (with
the -f option set), and starts updating the disks that it can see.
Creating and administering disk groups
Handling conflicting configuration copies
244