I would like to know whether (and how) ES protects me from data loss in the following case:
I have an index with the default 5 shards, spread to three machines. The index has replica count of 1 (two replicas).
In the default setting if one of the replicas fail, writes still succeed.
So what happens when I loose one machine, which is the slave for shard 1, write to the shard, which gets into the shard 1 master, then I loose shard 1 master?
A write has been acknowledged, but the shard was not fully replicated to the set replica count.
Now if the previous shard 1 slave comes up, will I loose the acknowledged write, or ES knows that previous shard 1 master had a newer version of the index and won't let it come up until the old shard 1 master comes up?
Does ES has a safety mechanism which covers multiple node losses?