[CentOS] disk I/O problems with LSI Logic RAID controller

Andrzej Szymanski szymans at agh.edu.pl
Thu Feb 11 07:46:01 UTC 2010


On 2010-02-09 18:15, Fernando Gleiser wrote:
> Every time we try to copy some large file to the storage-based file system, the disk utilization see-saws up to 100% to several seconds of inactivity, to climb up again to 100% and so forth.
> Here are a snip from the iostat -kx 1:
>
> Device:         rrqm/s   wrqm/s   r/s   w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
> sdb1              0.00 133811.00  0.00 1889.00     0.00 513660.00   543.84   126.24   65.00   0.47  89.40

The iostat output looks good to me for the RAID setup you have.
I'd look for the problem in a different place:

note the output of
cat /proc/sys/vm/dirty_background_ratio
and try
echo 1 > /proc/sys/vm/dirty_background_ratio
whether it helps.

Andrzej


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