I think aws uses drbd (http://www.drbd.org/ http://www.drbd.org/) for replicating the writes to the standby. Among the replication modes of drbd suggested here:

I think aws uses drbd (http://www.drbd.org/ http://www.drbd.org/) for replicating the writes to the standby. Among the replication modes of drbd suggested here: http://www.drbd.org/users-guide-emb/s-replication-protocols.html http://www.drbd.org/users-guide-emb/s-replication-protocols.... I suspect they probably use B and landed in a state where packets got delivered but werent written on the standby.