Can you explain the concept of split brain in distributed systems?

The split brain concept in distributed systems occurs when a cluster or group of nodes loses connectivity between its parts, but each part continues to operate and make decisions independently. This leads to a state where two or more parts of the system consider themselves active and attempt to perform the same operations, which can cause data conflicts and consistency issues.

For example, in a database cluster, if the connection between two halves of the cluster is lost, both may consider themselves the primary and accept writes, leading to data inconsistency.

To prevent split brain, quorum mechanisms are used — the system continues to operate only if a sufficient number of nodes are available, and external arbitration services or special distributed consensus algorithms (such as Raft, Paxos) are employed.