Symantec Veritas 5 - Manual (Page 87)

Configuring VCS clusters
for data integrity
This chapter includes the following topics:
■ About configuring VCS clusters for data integrity
■ About I/O fencing components
■ About setting up disk-based I/O fencing
■ Preparing to configure disk-based I/O fencing
■ Setting up disk-based I/O fencing manually
About configuring VCS clusters for data integrity
When a node fails, VCS takes corrective action and configures its components to
reflect the altered membership. If an actual node failure did not occur and if the
symptoms were identical to those of a failed node, then such corrective action
would cause a split-brain situation.
Some example scenarios that can cause such split-brain situations are as follows:
■ Broken set of private networks
If a system in a two-node cluster fails, the system stops sending heartbeats
over the private interconnects. The remaining node then takes corrective
action. The failure of the private interconnects, instead of the actual nodes,
presents identical symptoms and causes each node to determine its peer has
departed. This situation typically results in data corruption because both nodes
try to take control of data storage in an uncoordinated manner
■ System that appears to have a system-hang
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