‘Pubs & Bars With Raging Fires in Dublin’. This is important!
‘Anurag@AWS posts a quite interesting comment on Aurora failover: We asynchronously write to 6 copies and ack the write when we see four completions. So, traditional 4/6 quorums with synchrony as you surmised. Now, each log record can end up with a independent quorum from any other log record, which helps with jitter, but introduces some sophistication in recovery protocols. We peer to peer to fill in holes. We also will repair bad segments in the background, and downgrade to a 3/4 quorum if unable to place in an AZ for any extended period. You need a pretty bad failure to get a write outage.’ (via High Scalability)