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<div class="moz-cite-prefix">On 02/09/2017 06:39 PM, Joseph
Lorenzini wrote:<br>
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cite="mid:CAMvD0V+x3w6QzB1ELgAEG13D47vc8E4b3UMqC5u8b9Sr5ZT1ww@mail.gmail.com"
type="cite">
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<div>All:</div>
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<div>I read this in the gluster docs. Note I am not using
arbiter -- I am setting up volumes with full 3 replicas. In
this case, is this split brain scenario theoretical or has
this actually occurred? If so, what are the chances that this
could happen? In other words, aside from doing regular
snapshots, is this type of split brain scenario something I
should be planning in an unlikely disaster recovery scenario <b>or
</b>part of daily maintenance? Since the docs say its a corner
case, I am inferring that this is pretty unlikely.</div>
<div><br>
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<div><span
style="color:rgb(64,64,64);font-family:lato,proxima-nova,"helvetica
neue",arial,sans-serif;font-size:16px;background-color:rgb(252,252,252)">"There
is a corner case even with replica 3 volumes where the file
can end up in a split-brain. AFR usually takes range locks
for the {offset, length} of the write. If 3 writes happen on
the same file at non-overlapping {offset, length} and each
write fails on (only) one different brick, then we have AFR
xattrs of the file blaming each other."</span><br>
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<div><span
style="color:rgb(64,64,64);font-family:lato,proxima-nova,"helvetica
neue",arial,sans-serif;font-size:16px;background-color:rgb(252,252,252)"><br>
</span></div>
<div><span style="background-color:rgb(252,252,252)"><font
color="#404040" face="lato, proxima-nova, helvetica neue,
arial, sans-serif"><span style="font-size:16px"><a
moz-do-not-send="true"
href="https://gluster.readthedocs.io/en/latest/Administrator%20Guide/arbiter-volumes-and-quorum/#replica-2-and-replica-3-volumes">https://gluster.readthedocs.io/en/latest/Administrator%20Guide/arbiter-volumes-and-quorum/#replica-2-and-replica-3-volumes</a></span></font><br>
</span></div>
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<br>
<font color="#404040"><font face="lato, proxima-nova, helvetica
neue, arial, sans-serif">I don't think you should be bothered
about it too much as it is rare for split-brains to happen in
replica 3 (folks who have had experience otherwise, please
correct me:)). In the worst case, there are commands to resolve
split-brains as described in the link you shared above. <br>
<br>
Thanks,<br>
Ravi<br>
<br>
</font></font>
<blockquote
cite="mid:CAMvD0V+x3w6QzB1ELgAEG13D47vc8E4b3UMqC5u8b9Sr5ZT1ww@mail.gmail.com"
type="cite">
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<div><span style="background-color:rgb(252,252,252)"><font
color="#404040" face="lato, proxima-nova, helvetica neue,
arial, sans-serif"><span style="font-size:16px"><br>
</span></font></span></div>
<div><span style="background-color:rgb(252,252,252)"><font
color="#404040" face="lato, proxima-nova, helvetica neue,
arial, sans-serif"><span style="font-size:16px">Thanks,</span></font></span></div>
<div><span style="background-color:rgb(252,252,252)"><font
color="#404040" face="lato, proxima-nova, helvetica neue,
arial, sans-serif"><span style="font-size:16px">Joe</span></font></span></div>
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