glusterfs.git/tests/bugs/replicate/bug-1539358-split-brain-detection.t, branch v8dev GlusterFS is a distributed file-system capable of scaling to several petabytes. It aggregates various storage bricks over Infiniband RDMA or TCP/IP interconnect into one large parallel network file system. afr: don't treat all cases all bricks being blamed as split-brain 2018-02-01T14:17:50+00:00 Ravishankar N ravishankar@redhat.com 2018-01-28T08:20:47+00:00 0e6e8216823c2d9dafb81aae0f6ee3497c23d140 Problem: We currently don't have a roll-back/undoing of post-ops if quorum is not met. Though the FOP is still unwound with failure, the xattrs remain on the disk. Due to these partial post-ops and partial heals (healing only when 2 bricks are up), we can end up in split-brain purely from the afr xattrs point of view i.e each brick is blamed by atleast one of the others. These scenarios are hit when there is frequent connect/disconnect of the client/shd to the bricks while I/O or heal are in progress. Fix: Instead of undoing the post-op, pick a source based on the xattr values. If 2 bricks blame one, the blamed one must be treated as sink. If there is no majority, all are sources. Once we pick a source, self-heal will then do the heal instead of erroring out due to split-brain. Change-Id: I3d0224b883eb0945785ade0e9697a1c828aec0ae BUG: 1539358 Signed-off-by: Ravishankar N <ravishankar@redhat.com> 
Problem:
We currently don't have a roll-back/undoing of post-ops if quorum is not
met. Though the FOP is still unwound with failure, the xattrs remain on
the disk.  Due to these partial post-ops and partial heals (healing only when
2 bricks are up), we can end up in split-brain purely from the afr
xattrs point of view i.e each brick is blamed by atleast one of the
others. These scenarios are hit when there is frequent
connect/disconnect of the client/shd to the bricks while I/O or heal
are in progress.

Fix:
Instead of undoing the post-op, pick a source based on the xattr values.
If 2 bricks blame one, the blamed one must be treated as sink.
If there is no majority, all are sources. Once we pick a source,
self-heal will then do the heal instead of erroring out due to
split-brain.

Change-Id: I3d0224b883eb0945785ade0e9697a1c828aec0ae
BUG: 1539358
Signed-off-by: Ravishankar N <ravishankar@redhat.com>