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I'm seeing a problem on my fairly fresh RHEL gluster install. Smells
to me like a parallelism problem on the server.<br>
<br>
If I mount a gluster volume via NFS (using glusterd's internal NFS
server, nfs-kernel-server) and read a directory from multiple
clients *in parallel*, I get inconsistent results across servers.
Some files are missing from the directory listing, some may be
present twice!<br>
<br>
Exactly which files (or directories!) are missing/duplicated varies
each time. But I can very consistently reproduce the behaviour.<br>
<br>
You can see a screenshot here: <a class="moz-txt-link-freetext" href="http://imgur.com/JU8AFrt">http://imgur.com/JU8AFrt</a><br>
<br>
The replication steps are:<br>
* clusterssh to each NFS client<br>
* <tt>unmount /gv0</tt> (to clear cache)<br>
* <tt>mount /gv0</tt> [1]<br>
* <tt>ls -al </tt><tt>/gv0/common/apache-jmeter-2.9/bin</tt>
(which is where I first noticed this)<br>
<br>
Here's the rub: if, instead of doing the 'ls' in parallel, I do it
in series, it works just fine (consistent correct results
everywhere). But hitting the gluster server from multiple clients <b>at
the same time</b> causes problems.<br>
<br>
I can still stat() and open() the files missing from the directory
listing, they just don't show up in an enumeration.<br>
<br>
Mounting gv0 as a gluster client filesystem works just fine.<br>
<br>
Details of my setup:<br>
2 × gluster servers: 2×E5-2670, 128GB RAM, RHEL 6.4 64-bit,
glusterfs-server-3.3.1-1.el6.x86_64 (from EPEL)<br>
4 × NFS clients: 2×E5-2660, 128GB RAM, RHEL 5.7 64-bit,
glusterfs-3.3.1-11.el5 (from kkeithley's repo, only used for
testing)<br>
gv0 volume information is below<br>
bricks are 400GB SSDs with ext4[2]<br>
common network is 10GbE, replication between servers happens over
direct 10GbE link.<br>
<br>
I will be testing on xfs/btrfs/zfs eventually, but for now I'm on
ext4. <br>
<br>
Also attached is my chatlog from asking about this in #gluster<br>
<br>
[1]: fstab line is: <tt>fearless1:/gv0 /gv0 nfs
defaults,sync,tcp,wsize=8192,rsize=8192 0 0</tt><br>
[2]: yes, I've turned off dir_index to avoid That Bug. I've run the
d_off test, results are here: <a class="moz-txt-link-freetext" href="http://pastebin.com/zQt5gZnZ">http://pastebin.com/zQt5gZnZ</a><br>
<br>
----<br>
<tt>gluster> volume info gv0</tt><tt><br>
</tt><tt> </tt><tt><br>
</tt><tt>Volume Name: gv0</tt><tt><br>
</tt><tt>Type: Distributed-Replicate</tt><tt><br>
</tt><tt>Volume ID: 20117b48-7f88-4f16-9490-a0349afacf71</tt><tt><br>
</tt><tt>Status: Started</tt><tt><br>
</tt><tt>Number of Bricks: 8 x 2 = 16</tt><tt><br>
</tt><tt>Transport-type: tcp</tt><tt><br>
</tt><tt>Bricks:</tt><tt><br>
</tt><tt>Brick1:
fearless1:/export/bricks/500117310007a6d8/glusterdata</tt><tt><br>
</tt><tt>Brick2:
fearless2:/export/bricks/500117310007a674/glusterdata</tt><tt><br>
</tt><tt>Brick3:
fearless1:/export/bricks/500117310007a714/glusterdata</tt><tt><br>
</tt><tt>Brick4:
fearless2:/export/bricks/500117310007a684/glusterdata</tt><tt><br>
</tt><tt>Brick5:
fearless1:/export/bricks/500117310007a7dc/glusterdata</tt><tt><br>
</tt><tt>Brick6:
fearless2:/export/bricks/500117310007a694/glusterdata</tt><tt><br>
</tt><tt>Brick7:
fearless1:/export/bricks/500117310007a7e4/glusterdata</tt><tt><br>
</tt><tt>Brick8:
fearless2:/export/bricks/500117310007a720/glusterdata</tt><tt><br>
</tt><tt>Brick9:
fearless1:/export/bricks/500117310007a7ec/glusterdata</tt><tt><br>
</tt><tt>Brick10:
fearless2:/export/bricks/500117310007a74c/glusterdata</tt><tt><br>
</tt><tt>Brick11:
fearless1:/export/bricks/500117310007a838/glusterdata</tt><tt><br>
</tt><tt>Brick12:
fearless2:/export/bricks/500117310007a814/glusterdata</tt><tt><br>
</tt><tt>Brick13:
fearless1:/export/bricks/500117310007a850/glusterdata</tt><tt><br>
</tt><tt>Brick14:
fearless2:/export/bricks/500117310007a84c/glusterdata</tt><tt><br>
</tt><tt>Brick15:
fearless1:/export/bricks/500117310007a858/glusterdata</tt><tt><br>
</tt><tt>Brick16:
fearless2:/export/bricks/500117310007a8f8/glusterdata</tt><tt><br>
</tt><tt>Options Reconfigured:</tt><tt><br>
</tt><tt>diagnostics.count-fop-hits: on</tt><tt><br>
</tt><tt>diagnostics.latency-measurement: on</tt><tt><br>
</tt><tt>nfs.disable: off</tt><tt><br>
</tt><tt>----</tt><br>
<br>
<pre class="moz-signature" cols="72">--
Michael Brown | `One of the main causes of the fall of
Systems Consultant | the Roman Empire was that, lacking zero,
Net Direct Inc. | they had no way to indicate successful
☎: +1 519 883 1172 x5106 | termination of their C programs.' - Firth
</pre>
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