Speaking of RAID arrays, one thing that can compromise performance is having write caching turned off, which, it is my understanding, should be done for safety of the data if the RAID controller is not equipped with it's own battery backup.<br>
<br>GC<br><br><div class="gmail_quote">On Thu, May 6, 2010 at 1:22 PM, JK <span dir="ltr"><<a href="mailto:jknapka@kneuro.net">jknapka@kneuro.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div class="im">On 5/6/2010 9:39 AM, Jim Kinney wrote:<br>
> Look through the hdparm variables and see if your drive(s) are in some<br>
> stupid/slow mode.<br>
<br>
<br>
</div>Begging the question: what counts as "stupid/slow"? I know that having<br>
DMA turned off, or set wrong, will kill performance. What else should<br>
be checked?<br>
<br>
And Google leads me to:<br>
<br>
<a href="http://www.linuxclues.com/articles/20.htm" target="_blank">http://www.linuxclues.com/articles/20.htm</a><br>
<br>
In general, PIO modes are slowest and UDMA modes are fastest, correct?<br>
I remember a while back I had a 160G RAID array that was literally<br>
taking days to rebuild. Turned out the HDs were in like PIO3 or something.<br>
Changed to UDMA4 and the rebuild completed in fifteen minutes.<br>
<br>
-- JK<br>
<font color="#888888"><br>
<br>
--<br>
Forget Jesus: stars died so that you could be here today.<br>
- physicist Lawrence Krauss<br>
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