I see. So if I switch to a different cluster quorum model, I may get split-brain which would need manual intervention should a node go missing? Adding an arbiter involves creating a volume from scratch? You can't just add it to an existing volume. On Fri, Jan 20, 2017 at 2:52 PM, Gambit15 <dougti+gluster at gmail.com> wrote:>> Type: Distributed-Replicate >> Number of Bricks: 2 x 2 = 4 > > > With that setup, you lose quorum if you lose any one node. > Brick 1 replicates to brick 2, and brick 3 replicates to brick 4. If any one > of those goes down, quorum falls to <51%, which locks the brick under the > default settings. > > If you've only got 4 servers to play with, I suggest you move to replication > 3 arbiter 1. Put the arbiter for servers 1 & 2 on server 3, and the arbiter > for servers 3 & 4 on server 1. > > https://gluster.readthedocs.io/en/latest/Administrator%20Guide/arbiter-volumes-and-quorum/ >
Ah yeah, I did wonder about that but I thought quorum was based on all bricks, not just the replica set. Guess my first instinct was right !> I see. So if I switch to a different cluster quorum model, I may get > split-brain which would need manual intervention should a node go > missing?Yes> > Adding an arbiter involves creating a volume from scratch? You can't > just add it to an existing volume. >You can, I think in your case you'd need to remove 2 nodes (removing the distributed part), then add a brick to go to replica 3, then you should be able to add the two arbiters at once. If you can afford downtime creating a new volume is clearly a lot simpler :) -- Kevin Lemonnier PGP Fingerprint : 89A5 2283 04A0 E6E9 0111 -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: Digital signature URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20170120/38469f7b/attachment.sig>