Re: High iowait

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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?


On 8/22/06, Lothar Braun <mail@xxxxxxxxxx> wrote:

On Tuesday 22 August 2006 04:31, jassduec@xxxxxxxxx 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,
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
then do more sophisticated work than waiting)


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