Stateless master nodes

[darefilz]

Hi there,

we're planning to switch from data+master design to dedicated data and dedicated master design as a lot of people already did.
The data nodes are on physical machines, the master nodes go to docker containers. Fact: these containers can't store persistent data. The master nodes do have access to their configured data directories inside the containers, but we can't mount that directories outside, so when a container goes down the data is gone.
Now, the key question is: how bad can that be? I mean, what's the worst case that can happen, if the cluster state and whatever the master nodes save is deleted before the master nodes come up again?

Thanks and regards
df

[ywelsch (Yannick Welsch)]

how bad can that be?

This is horrible. You'll lose all templates and other global metadata when restarting the master nodes. Also, this greatly increases the risk of data loss. Master nodes are not supposed to be stateless, don't do that.