On Fri, Sep 22, 2017 at 12:27:46PM +0530, Ravishankar N wrote: > Hello, > > In AFR we currently allow look-ups to pass through without taking into > account whether the lookup is served from the good or bad brick. We always > serve from the good brick whenever possible, but if there is none, we just > serve the lookup from one of the bricks that we got a positive reply from. > > We found a bug [1] due to this behavior were the iatt values returned in > the lookup call was bad and caused the client to hang. The proposed fix [2] > was to fail look ups when we definitely know the lookup can't be trusted (by > virtue of AFR xattrs indicating the replies we got from the up bricks are > indeed bad). > > Note that this fix is *only* for replica 3 or arbiter volumes (not replica > 2, where there is no notion of quorum). But we want to 'harden' the fix by > not allowing any look ups at all if quorum is not met (or) it is met but > there are no good copies. > > Some implications of this: > > -If a file ends up in data/meta data split-brain in replica 3/arbiter (rare > occurrence), we won't be able to delete it from the mount. > > -Even if the only brick that is up is the good copy, we still fail it due to > lack of quorum. > > Does any one have comments/ feedback? I think additional improvements for correctness outweigh the two negative side-effects that you listed. Possibly the 2nd point could get some confusion from users. "it always worked before" may be a reason to add a volume option for this? That is something you can consider, but if you deem that overkill then I'm ok with that too. Thanks, Niels > > Thanks, > > Ravi > > [1] https://bugzilla.redhat.com/show_bug.cgi?id=1467250 > > [2] https://review.gluster.org/#/c/17673/ (See review comments on the > landing page if interested) > > _______________________________________________ > Gluster-devel mailing list > Gluster-devel@xxxxxxxxxxx > http://lists.gluster.org/mailman/listinfo/gluster-devel
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