Re: 3ware disk latency?

From: dean gaudet
Date: Wed Jul 26 2006 - 22:58:55 EST

On Wed, 26 Jul 2006, adam radford wrote:

> On 7/26/06, dean gaudet <dean@xxxxxxxxxx> wrote:
> >
> > unfortunately when i did the experiment i neglected to perform
> > simultaneous tests on more than one 3ware unit on the same controller. i
> > got great results from a raid1 or from a raid10 (even a raid5)... but
> > never i only tested one unit at a time.
> >
> Did you try setting /sys/class/scsi_host/hostX/cmd_per_lun to 256 / num_units
> ?

hmm doesn't look like i can do this in

# ls -l /sys/class/scsi_host/host0/cmd_per_lun
-r--r--r-- 1 root root 0 Jul 26 19:58 /sys/class/scsi_host/host0/cmd_per_lun
# echo 85 >!$
echo 85 >/sys/class/scsi_host/host0/cmd_per_lun
zsh: permission denied: /sys/class/scsi_host/host0/cmd_per_lun

it'll probably be sometime until i update this box past 2.6.16.x ... but
i'll keep it in mind and retry the experiment... thanks.

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