On Wed, Jun 13, 2018 at 11:16:32AM +1200, Thing wrote: > I am a bit lost here, why a replica 3 and arbiter 1? ie not replica2 > arbiter1? You'd have to ask the developers about that (I just use gluster, I'm not a dev). I agree that "replica 2 arbiter 1" seems more intuitive, but I suppose "replica 3 arbiter 1" could be seen as more technically accurate, if you look at it as three replicas, but one of the replicas only stores metadata instead of a full copy. > also no distributed part? is the distributed flag automatically > assumed? When you create a replicated volume and specify more bricks than the replica count, "distributed" is implied because that's the only way that it would make sense for a replica-2 volume to have 6 bricks. (See the "To create a distributed replicated volume" section in the docs at https://gluster.readthedocs.io/en/latest/Administrator%20Guide/Setting%20Up%20Volumes/ if you'd like to confirm that omitting "distributed" is correct.) Come to think of it, that might also be why arbiter configurations are considered to be "replica 3" instead of "replica 2" - you're specifying bricks in groups of three, so it makes the syntax checking a little easier if you can just say "number of bricks must be a multiple of replica count" without adding a special case to increment the replica count if there's an arbiter also specified. > with a replica3 then there is a quorum (2 of 3) so no arbiter is > needed? Correct. Arbiters are only needed (or allowed) in the specific case of replica 2+arbiter. Per the docs at https://gluster.readthedocs.io/en/latest/Administrator%20Guide/arbiter-volumes-and-quorum/ "Note: Volumes using the arbiter feature can only be replica 3 arbiter 1" > I have this running already like this so I am assuming its robust? Yes, it definitely should be! The only disadvantage of replica 3 vs. replica 2+A is the lower storage capacity. > So on each gluster node I have an-unused 120gb data1 partition which is > left over from the OS install so the arbiter volume could go here? > > in which case? > > gluster volume create my-volume replica 2 arbiter 1 host1:/path/to/brick > host2:/path/to/brick (arb-)host3:/path/to/brick2 host4:/path/to/brick > host5:/path/to/brick (arb-)host6:/path/to/brick2 host3:/path/to/brick > host6:/path/to/brick (arb-)host1:/path/to/brick2 > > is this a sane command? Yep, looks reasonable to me aside from the "replica 2" needing to be "replica 3". -- Dave Sherohman _______________________________________________ Gluster-users mailing list Gluster-users@xxxxxxxxxxx http://lists.gluster.org/mailman/listinfo/gluster-users
