* High iowait
@ 2006-08-22 2:31 jassduec
2006-08-22 9:38 ` Lothar Braun
0 siblings, 1 reply; 6+ messages in thread
From: jassduec @ 2006-08-22 2:31 UTC (permalink / raw)
To: linux-admin, linux-config
I have a storage raid attached to my linux server running CentOS 4.3
kernel 2.6.9-39.0.2.ELsmp. My server goes into huge iowait when i try
to read/write lot of data to the storage device. How can i debug
whether the problem is with the storage device or some setting of the
operating system. Is there any known issue with this kernel? How can i
tune my system to reduce iowait time?
TIA
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: High iowait
2006-08-22 2:31 High iowait jassduec
@ 2006-08-22 9:38 ` Lothar Braun
2006-08-23 16:10 ` jassduec
0 siblings, 1 reply; 6+ messages in thread
From: Lothar Braun @ 2006-08-22 9:38 UTC (permalink / raw)
To: jassduec; +Cc: linux-admin, linux-config
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Hi,
On Tuesday 22 August 2006 04:31, jassduec@gmail.com wrote:
> I have a storage raid attached to my linux server running CentOS 4.3
> kernel 2.6.9-39.0.2.ELsmp. My server goes into huge iowait when i try
> to read/write lot of data to the storage device. How can i debug
> whether the problem is with the storage device or some setting of the
> operating system. Is there any known issue with this kernel? How can i
> tune my system to reduce iowait time?
Why should you want to reduce the iowait time? Iowait, as shown by top, means
afaik that there are some processes waiting for io to complete and nothing
else to do for the processor.
If you're running some CPU eating processes while your I/O operations are
performed, then the iowait value should go down (this is because your CPU can
then do more sophisticated work than waiting)
Regards,
Lothar
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: High iowait
2006-08-22 9:38 ` Lothar Braun
@ 2006-08-23 16:10 ` jassduec
2006-08-24 1:01 ` terry white
2006-08-24 20:06 ` Art Wildman
0 siblings, 2 replies; 6+ messages in thread
From: jassduec @ 2006-08-23 16:10 UTC (permalink / raw)
To: Lothar Braun; +Cc: linux-admin, linux-config
Lothar,
Thanks for the reply.
Basically i am not able to achieve the kind of throughput which i
should get from my RAID system. And i think the OS is the culprit
(some bug in the vendor kernel) since for some reason it goes into
huge iowaits preventing the applications to read/write more data. How
can i debug whether the problem is with the OS or with the device?
TIA
On 8/22/06, Lothar Braun <mail@lobraun.de> wrote:
> Hi,
>
> On Tuesday 22 August 2006 04:31, jassduec@gmail.com wrote:
> > I have a storage raid attached to my linux server running CentOS 4.3
> > kernel 2.6.9-39.0.2.ELsmp. My server goes into huge iowait when i try
> > to read/write lot of data to the storage device. How can i debug
> > whether the problem is with the storage device or some setting of the
> > operating system. Is there any known issue with this kernel? How can i
> > tune my system to reduce iowait time?
>
> Why should you want to reduce the iowait time? Iowait, as shown by top,
> means
> afaik that there are some processes waiting for io to complete and nothing
> else to do for the processor.
> If you're running some CPU eating processes while your I/O operations are
> performed, then the iowait value should go down (this is because your CPU
> can
> then do more sophisticated work than waiting)
>
> Regards,
> Lothar
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2006-08-25 18:59 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-08-22 2:31 High iowait jassduec
2006-08-22 9:38 ` Lothar Braun
2006-08-23 16:10 ` jassduec
2006-08-24 1:01 ` terry white
2006-08-24 20:06 ` Art Wildman
2006-08-25 18:59 ` how tell what specific device is sending an interrupt? tom arnall
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