Can you give some more info about the happening writes and truncates. Are they all happening on the same FD? Is it possible to get paste strace -f output of the ftpd performing writes on the gluster mount?
Avati
On Sat, Jul 16, 2011 at 5:49 PM, Emmanuel Dreyfus <manu@xxxxxxxxxx> wrote:
Emmanuel Dreyfus <manu@xxxxxxxxxx> wrote:
> client# md5 gnusrc.tgz
> MD5 (gnusrc.tgz) = 471a73c374ec2b5733571c01647a69d5
>
> server# md5 /export/wd3a/tmp/gnusrc.tgz
> MD5 (/export/wd3a/tmp/gnusrc.tgz) = cf03446a7f31713002ef3b74020b173f
Here are the results of my investigations. It seems this is caused on
the client, by reordering of ftruncate() and write() by
performance/write-behind
Above write-behind, we get this:
write(sizeA, offsetA)
ftruncate(offsetB)
write(sizeB, offsetB)
write(sizeC, offsetC)
write(sizeD, offsetD)
And below, this turns into:
write(sizeA, offsetA)
write(sizeB, offsetB)
write(sizeC, offsetC)
ftruncate(offsetB)
write(sizeD, offsetD)
Result is that data between offsetB and offsetD is filled with zeros.
Removing the performance/write-behind xlator on the client fixes the
problem.
Nobody else got this problem? It may be NetBSD-specific, since the
ftruncate() come from FUSE SETATTR issued by the NetBSD kernel to update
the file size. I could filter out such messages, but I am not sure it
would not have side effects.
--
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu@xxxxxxxxxx
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