Re: High write latency, iowait, slow writes 2.6.9

["Paul A. Sumner" <paul@zanfx.com>]

Thanks... I've tried the as, deadline and cfq schedulers. Deadline is
giving me the best results. I've also tried tweaking the stuff in
/sys/block/sda/queue/iosched/.

For lack of a better way of describing it, it seems like something is
thrashing.

Miquel van Smoorenburg wrote:
> In article <41E4BB99.90908@zanfx.com>,
> Paul A. Sumner <paul@zanfx.com> wrote:
> 
>>I have a new server that during big io tasks, e.g., bonnie++ and
>>tiobench testing, becomes very unresponsive. Both bonnie++ and tiobench
>>show good read performance, but the write performance lags, max
>>latencies are into the *minutes* and it experiences extended high
>>iowait. I'm guessing the iowait may not be a real problem. The machine
>>is as follows:
> 
> 
> Try another IO scheduler (boot with elevator=deadline or elevator=cfq
>  on the kernel command line)
> 
> Mike.
> 
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-- 
Paul A. Sumner
Principal Software Engineer

Moore Iacofano Goltsman, Inc. (MIG)
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