I run a few two node glusterfs instances, but always have a third machine acting as an arbiter. I am with Jeff on this one, better safe than sorry. Setting up a 3rd system without bricks to achieve quorum is very easy. Diego On Fri, Mar 4, 2016 at 10:40 AM, Jeff Darcy <jdarcy@xxxxxxxxxx> wrote: >> I like the default to be 'none'. Reason: If we have 'auto' as quorum for >> 2-way replication and first brick dies, there is no HA. If users are >> fine with it, it is better to use plain distribute volume > > "Availability" is a tricky word. Does it mean access to data now, or > later despite failure? Taking a volume down due to loss of quorum might > be equivalent to having no replication in the first sense, but certainly > not in the second. When the possibility (likelihood?) of split brain is > considered, enforcing quorum actually does a *better* job of preserving > availability in the second sense. I believe this second sense is most > often what users care about, and therefore quorum enforcement should be > the default. > > I think we all agree that quorum is a bit slippery when N=2. That's > where there really is a tradeoff between (immediate) availability and > (highest levels of) data integrity. That's why arbiters showed up first > in the NSR specs, and later in AFR. We should definitely try to push > people toward N>=3 as much as we can. However, the ability to "scale > down" is one of the things that differentiate us vs. both our Ceph > cousins and our true competitors. Many of our users will stop at N=2 no > matter what we say. However unwise that might be, we must still do what > we can to minimize harm when things go awry. > _______________________________________________ > Gluster-users mailing list > Gluster-users@xxxxxxxxxxx > http://www.gluster.org/mailman/listinfo/gluster-users _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxxx http://www.gluster.org/mailman/listinfo/gluster-devel
