[Gluster-users] gluster client performance

Pavan T C tcp at gluster.com
Wed Jul 27 06:25:48 UTC 2011


> I don't know why my writes are so slow compared to reads. Let me know
> if you're able to get better write speeds with the newer version of
> gluster and any of the configurations (if they apply) that I've
> posted. It might compel me to upgrade.

 From your documentation of nfsspeedtest, I see that the reads can 
happen either via dd or via perl's sysread. I'm not sure if one is 
better over the other.

Secondly - Are you doing direct IO on the backend XFS ? If not, try it 
with direct IO so that you are not misled by the memory situation in the 
system at the time of your test. It will give a clearer picture of what 
your backend is capable of.

Your test is such that you write a file and immediately read the same 
file back. It is possible that a good chunk of it is cached on the 
backend. After the write, do a flush of the filesystem caches by using:
echo 3 > /proc/sys/vm/drop_caches. Sleep for a while. Then do the read.
Or as suggested earlier, resort to direct IO while testing the backend FS.


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