Comparison
FailovervsMitigation
Failover
the primary stopped answering and something promoted a replica, and now you find out how much of the last few seconds you lost.
Promoting a replica to leader when the current leader is deemed dead. Under asynchronous replication it loses any unreplicated writes; under synchronous it may refuse to proceed. The hard part is the deeming: too eager and you failover on a network blip, too slow and the outage is the timeout.
Full entry →Mitigation
you failed over to the other region at 02:40 and went back to bed with the bug still there.
An action that reduces or removes the impact without fixing the underlying cause. It is the correct goal during an incident, and confusing it with a fix is how people stay up until dawn chasing a root cause with customers still affected. A mitigation deployed and then forgotten is its own risk, which is why the follow-up work is tracked separately and explicitly.
Full entry →