Re: Scsipi guru needed...

["Michael L. Hitch" <mhitch%lightning.msu.montana.edu@localhost>]

On Sun, 30 Nov 2008, Anders Magnusson wrote:

> I have been trying to find out why the performance of the ciss controller 
> (Compaq raid) in
> DL38x is really bad, but as I don't understand anything about the scsipi
> layer (are there any docs?) I must ask around.  All this is really strange.
>
> Writing data to the raw sd device (bs=64k) gets just over 7MB/s, which is 
> quite slow.
> Some debugging showed that:
> - A write transfer (from given to the ctlr to interrupt) takes 8ms.  Ok, no 
> write cache on the ctlr maybe?

  Does your controller have a battery backup?  I've found that without the
battery backup, the controller does not use any write cache and write 
speeds are significantly reduced.

--
Michael L. Hitch                        mhitch%montana.edu@localhost
Computer Consultant
Information Technology Center
Montana State University        Bozeman, MT     USA