[Gluster-users] Strange performance issues on Debian/Lenny compared to Ubuntu

[Olivier Le Cam]

Hi -

Thank you Raghavendra for detailed reply and information.

Raghavendra G wrote:
> I am seeing write-behind aggregating large number of writes into a single
> large write on Ubuntu client, but not on lenny client. This is the cause of
> large number of frames on network. This can also be the cause of slower
> performance on lenny.
> 
> Can you set "option enable-trickling-writes false" in write-behind on lenny
> and rerun tests. That will set write-behind to do more aggressive
> aggregation. We are eagerly waiting for your results :).

This is just a bit better with this option disabled:

* with "option enable-trickling-writes false":
     ~# dd if=/dev/zero of=/mnt/test_file count=262144 bs=1024
     262144+0 enregistrements lus
     262144+0 enregistrements écrits
     268435456 bytes (268 MB) copied, 72,7446 s, 3,7 MB/s

* and without it:
     ~# dd if=/dev/zero of=/mnt/test_file count=262144 bs=1024
     262144+0 enregistrements lus
     262144+0 enregistrements écrits
     268435456 bytes (268 MB) copied, 87,8484 s, 3,1 MB/s

(each test repeated several times with very little variances: +/- 0.1 MB/s).

BTW, did you see the comparative results I have posted, using 
Deban/Lenny on the same hardware but with either a 2.6.18 and 2.6.26 
vernel version? It seems that kernel version is very critical in the way 
write-behind is able to do large aggregation.

> However I am still investigating what is the reason behind write-behind on
> Ubuntu doing large aggregation but not on lenny.

Thank's a lot! I guess many people will appreciate!

Kind regards,
-- 
Olivier