Re: [tlug] Disk I/O bottleneck: how to solve?

["Shimpei Yamashita" <shimpei@example.com>]

On 9/4/2002, "Jean-Christian Imbeault" <jean_christian@example.com>
wrote:
>>By the way, if you didn't have 200M of free RAM, the
>>Disk I/O bottleneck might have been coming from
>>thrashing
>
>I don't think there is any thrashing going on. It's a web server and I
think
>there just are too many requests coming in. That and the fact that
apache
>writes 1Gb logs each day. (And yes I do need all the info the 1Gb log, so
no
>I can't turn off logging).

Are the log files on a different physical disk and bus from the files
Apache is serving? You definitely don't want those on the same disk;
otherwise the disk head ends up spending most of its time seeking.

BTW, Linux does use free memory to buffer disks, out of the box. No 
configuration necessary. 200M of free RAM isn't going to help you much
with logging anyway; what makes you think there is any performance
gain in keeping a 200MB backlog of writes that's being constantly
replenished at 1GB/day? It'll save you for exactly 0.2 days, after which
you're in no better shape than if you never had buffering in the first
place.

Shimpei.


-- 
Shimpei Yamashita
shimpei@example.com