[Gluster-users] Different file in two bricks, no split-brain detected

Chaloulos, Klearchos (Nokia - GR/Athens)
Tue, 26 Jan 2016 16:27:38 -0000

Description of problem:
My setup has 5 gluster volumes, and each of them has 2 bricks as backend.
When I copy a large file (100MB) in a gluster volume, 9/10 times it works OK.
But about 1 in 10 times the resulting md5 is wrong. After checking I found that
the file in one brick has the correct md5sum, while the file in the other brick
has a wrong md5sum. The size of the two files is the same.
By running "cmp -l <correct_file> <wrong_file>"
I found that the difference was in 49 bytes. So the files in the two bricks had
the same size, but 49 files were different. Interestingly enough I saw the same
number of 49 bytes being different at every check that I made.

Do you know what might cause this behavior, has anyone seen something like this
before? Is this a bug in glusterfs?


Version-Release number of selected component (if applicable):
glusterfs 3.7.5 built on Nov 19 2015 16:29:59
Repository revision: git://git.gluster.com/glusterfs.git
Copyright (c) 2006-2011 Gluster Inc. <http://www.gluster.com>
GlusterFS comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of GlusterFS under the terms of the GNU General
Public License.


How reproducible:
Not easy to reproduce, about 1 in 10 times in some environments, not
reproducible at all in other environments.

Steps to Reproduce:
1. scp <100MB file> <path in gluster volume>

Actual results:
1. md5sum of destination should be the same as the source
2. If checksum of files is different between the two bricks, the command
"gluster volume heal <vol-name> info split-brain" should return
that the two bricks are in split-brain.


Expected results:
1. 1 in 10 times the destination file has incorrect checksum. Size is the same,
but 49 bytes are altered.
2. "gluster volume heal <vol-name> info split-brain" does not
return that the bricks are in split-brain, even though the checksum of the file
in the two bricks is different. The size of the file is the same in the two
bricks. But 49 bytes are altered.

Additional info:

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