[ceph-users] Re: How safe is k=2, m=1, min_size=2?

On Fri, Dec 13, 2019 at 10:36 AM Dan van der Ster <dan@vanderster.com> wrote:

Hi all,

We have said in the past that an EC pool should have min_size=k+1, for the same reasons that a replica 3 pool needs min_size=2. And we've heard several stories about replica 3, min_size=1 leading to incomplete PGs.

Taking a quick poll -- did anyone ever suffer an outage on a pool with k=2, m=1, min_size=2?

I don't know about losses, but I'd expect this configuration to be slightly less safe than replica 2 — you lose data after 2 related disks crash, but you have 3 related disks that can fail instead of only 2. -Greg