Re: 3ware disk latency?

[Alan Cox]

Ar Mer, 2006-07-26 am 09:52 -0700, ysgrifennodd dean gaudet:
> On Mon, 10 Jul 2006, Jan Kasprzak wrote:
> 
> > 	Does anybody experience the similar latency problems with
> > 3ware 95xx controllers? Thanks,
> 
> i think the 95xx is really bad at sharing its cache fairly amongst 
> multiple devices... i have a 9550sx-8lp with 3 exported units: a raid1, a 
> raid10 and a jbod.  i was zeroing the jbod with dd and it absolutely 
> destroyed the latency of the other two units.

Even on the older 3ware I found it neccessary to bump up the queue sizes
for the 3ware. There's a thread from about 6 months ago (maybe a bit
more) with Jeff Merkey included where it made a huge difference to his
performance playing with the parameters. Might be worth a scan through
the archive.

Alan

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