Hi Strahil and Ravi, Thank you very much for your replies, that makes sense.
On Thu, 21 Oct 2021 at 03:25, Ravishankar N <ravishanka...@pavilion.io> wrote: > Hi David, > > On Wed, Oct 20, 2021 at 6:23 AM David Cunningham < > dcunning...@voisonics.com> wrote: > >> Hello, >> >> I've a few questions about conflict resolution in a net-split scenario: >> >> 1. What are the default values for cluster.server-quorum-type and >> cluster.server-quorum-ratio? (at the moment "gluster volume info gvol0" >> does not report either) >> >> $gluster volume get gvol0 cluster.server-quorum-type > $gluster volume get all cluster.server-quorum-ratio > > > >> 2. If there are 3 mirrored nodes and cluster.server-quorum-ratio is 50, >> and node1 and node2 are net-split from node3, then am I right in thinking >> that the volume on node3 will automatically shut down and prevent access >> thus preventing a conflict? >> >> Yes, the glusterd on node 3 will kill the brick processes on that node. > > >> 3. If there are 2 mirrored nodes and a net-split happens and >> cluster.server-quorum-ratio is 50 then: >> a) If existing file A is changed on node1 and node2 then the file will >> enter net-split state, right? >> > > Yes, for 2 node setups, you must set the ratio to 51% to avoid this. I'm > assuming that the 'changing' that you refer to is happening via fuse mounts > on each of these nodes. > > >> b) If existing file B is changed on node1 but not node2 then will the >> file enter a net-split state? >> > No. > > >> c) If new file C is written on node1 but not node2 then will the file >> enter a net-split state? >> >> No. > > >> 4. Is the outcome of conflict resolution at a file level the same whether >> node3 is a full replica or just an arbiter? >> >> server quorum feature is not related to replication. It really is a > glusterd thing and doesn't really help prevent split-brains, because > split-brains are caused by failed I/Os from clients and the clients can be > mounted even outside the storage pool. What you need to ensure is > that cluster.quorum-type (which is 'client' quorum) is set to auto for > replica 3 and arbiter. It already is by default. See > https://docs.gluster.org/en/latest/Administrator-Guide/arbiter-volumes-and-quorum/#split-brains-in-replica-volumes > for more info. > > -Ravi > >> Thank you very much for any advice, >> >> -- >> David Cunningham, Voisonics Limited >> http://voisonics.com/ >> USA: +1 213 221 1092 >> New Zealand: +64 (0)28 2558 3782 >> ________ >> >> >> >> Community Meeting Calendar: >> >> Schedule - >> Every 2nd and 4th Tuesday at 14:30 IST / 09:00 UTC >> Bridge: https://meet.google.com/cpu-eiue-hvk >> Gluster-users mailing list >> Gluster-users@gluster.org >> https://lists.gluster.org/mailman/listinfo/gluster-users >> > -- David Cunningham, Voisonics Limited http://voisonics.com/ USA: +1 213 221 1092 New Zealand: +64 (0)28 2558 3782
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