Just to add some more info: Funny enough what triggers this problem when you have master persistence turned down is, the lack of failover, if the reboot happen

Just to add some more info: Funny enough what triggers this problem when you have master persistence turned down is, the lack of failover, if the reboot happens fast enough, in case you are using Sentinel, for it to failover to a replica. So no failure was sensed at all, just the master magically wiped its data set. So from the point of view of distributed systems, if you want to analyze the sum of Redis replicated nodes + Sentinel, the problem is that the system is not designed to cope with nodes losing state on restarts. However it is possible to improve it, and I'm doing it, but before diskless replication it was IMHO pretty useless to have support for persistence-less operations in conjunction with replication, since the slaves to synchronize required anyway the master to save an RDB file on disk.