Re: I/O problem with sustained writes

[Andrew Morton]

Collectively Unconscious wrote:
> 
> We are having a problem with writes.
> They start at 14 M/s for the first hour and then drop to 2.5 M/s and stay
> that way. Reads do not seem effected and we've noticed this on the 2.2.16,
> 2.2.17, 2.2.18 and now the 2.2.19pre11 kernels.
> 
> These are SMP P-IIIs from 450 to 800 MHz. Redhat 6.2

I've seen something similar on Seagate ST313021A IDE drives.
After a few minutes their read throughput falls from 20
megs/sec to about 5.  Issuing *any* drive-setting command
brings the throughput back.  Even a command which the disk
doesn't support.

So I have a cron job which runs `hdparm -A1' once per minute.

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