split-brain
Competing nodes act as the same write authority after losing coordination.
Use this when An old primary resumes writes after a standby has been promoted.
without the term
“The old primary came back after promotion and both servers accept writes. Prevent competing authorities.”
with the term · How do you ask a model for split-brain?
Verify failover fencing: isolate the primary, promote safely, and prove the former primary cannot accept writes.
What is split-brain?
Split-brain occurs when separated nodes both believe they may own an exclusive role. Conflicting histories can result if both accept writes without the required coordination.
Why does split-brain matter when vibe coding?
An agent can implement promotion on a missed heartbeat without disabling the old writer.
How do you do split-brain?
Use the platform’s election and fencing mechanisms. In a disposable drill, isolate the primary and verify the old authority cannot write after promotion.
What goes wrong with split-brain?
A timeout shows that a node is unreachable, not that it is dead. Deliberate multi-leader replication has a different conflict contract.
Sources for this entry
- PostgreSQL: Failover
Promotion, client routing, preventing the old primary from continuing as a writer, and restoring redundancy.
- Ongaro and Ousterhout: Raft
Replicated-log consensus, majority voting, safe membership changes, and timing requirements for progress.
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