Hmm, I was be tempted to suggest that you were bitten by the gluster/ext4 readdir's d_off incompatibility issue (which got recently fixed <a href="http://review.gluster.org/4711/">http://review.gluster.org/4711/</a>). But you say it works fine when you do ls one at a time sequentially.<div>
<br></div><div>I just realized after reading your email that, in glusterfs, because we use the same anonymous fd for multiple client/application's readdir query, we have a race in the posix translator where two threads attempt to push/pull the same backend cursor in a chaotic way resulting in duplicate/lost entries. This might be the issue you are seeing, just guessing.</div>
<div><br></div><div>Will you be willing to try out a source cod patch on top of the git HEAD to rebuild your glusterfs and verify if it fixes the issue? Will really appreciate it!</div><div><br></div><div>Thanks,</div><div>
Avati<br><br><div class="gmail_quote">On Wed, Apr 3, 2013 at 2:37 PM, Michael Brown <span dir="ltr"><<a href="mailto:michael@netdirect.ca" target="_blank">michael@netdirect.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
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 href="http://imgur.com/JU8AFrt" target="_blank">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 href="http://pastebin.com/zQt5gZnZ" target="_blank">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><span class="HOEnZb"><font color="#888888"><br>
<br>
<pre 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
☎: <a href="tel:%2B1%20519%20883%201172%20x5106" value="+15198831172" target="_blank">+1 519 883 1172 x5106</a> | termination of their C programs.' - Firth
</pre>
</font></span></div>
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