Split Brain
A failure state in which multiple isolated participants simultaneously believe they are authoritative, risking conflicting state changes.
Distributed-Systems Context
Split brain occurs when isolated participants simultaneously act as authoritative owners. If both sides accept writes, state can diverge and later reconciliation may lose or conflict with data. Quorums, fencing tokens, leases, and external witnesses are mechanisms used to preserve one effective authority.
Failure-Model Boundary
A network partition alone is not split brain. Split brain is the authority failure that can result when a partition allows more than one side to continue acting as leader or owner.