[CentOS] Serial ATA hardware raid.

Sat Apr 16 17:52:35 UTC 2005
Harald Finnås <spamcatcher at lantrix.no>

Avtar Gill wrote on 16.04.2005 08:54:50:

> > Just have to mention it while I remember. If you decide on the 3ware 
> > 9500s controller, be aware that you HAVE to do some manual tuning. It 
> > performs like crap out of the box.
> I was wondering if you could expand on that.  What type of array(s) are 
> you using, which controller and any specific settings?

If memory serves, I had the worst performance on aa 7506-8 running R5 and 
MDK 10.1. Write performance was extremenly slow, so the box would use all 
memory for cache almost immidiately. This resulted in very high CPU, and 
the machine became unresponsive. After applying:

sysctl -w "vm.bdflush=0 500 0 0 500 3000 0 20 0"

it was back to normal. This works with 2.4 kernels only. With 2.6 this 
improves performance:

blockdev --setra 16384 /dev/sda

I'm pretty sure I found both these setting in the 3ware knowledgebase.


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