Split-brain (computing)

High-availability clusters clusters usually use a heartbeat private network connection which is used to monitor the health and status of each node in the cluster. One subtle, but serious condition every clustering software must be able to handle is split-brain.

Split-brain occurs when all of the private links go down simultaneously, but the cluster nodes are still running.

If that happens, each node in the cluster may mistakenly decide that every other node has gone down and attempt to start services that other nodes are still running. Having duplicate instances of services may cause data corruption on the shared storage.

This problem can lead to data inconsistency. To prevent it computers should use redundant communications and fall down to an auto-fencing mode when the peers look like down. This means, they should run in a limited mode to prevent data destroy