Subject: Re: Low AAC performance but only when tested through the file system
To: Olaf Seibert <rhialto@polderland.nl>
From: Bill Studenmund <wrstuden@netbsd.org>
List: current-users
Date: 11/30/2003 15:07:33
--gj572EiMnwbLXET9
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Sat, Nov 29, 2003 at 03:45:00PM +0100, Olaf Seibert wrote:
> On Fri 28 Nov 2003 at 19:25:05 -0800, Bill Studenmund wrote:
> > > So it's not like the card is not capable of proper transfer counts and
> > > speeds, it seems it is held back somehow by the file system or buffer
> > > cache.
> >=20
> > What is the setup of your raid volume?
>=20
> We have a RAID-5 of 5 U-320 SCSI disks of about 35 G each, and one hot
> spare. I have also attached the dmesg output and the disklabel.

What's your stripe depth? For optimal performance, you want it to be 16k. =
=20
The file system will do 64k i/o's. With 4 data drives & a 16k stripe
depth, a 64k i/o (on a 64k boundary) will hit all 4 drives at once.

Take care,

Bill

--gj572EiMnwbLXET9
Content-Type: application/pgp-signature
Content-Disposition: inline

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (NetBSD)

iD8DBQE/yng1Wz+3JHUci9cRAslcAKCQqE7+xYe6UmuTB8K5go/+wb+XvACeM2rY
7F5Yyt6m50cNVIETGEhOSDY=
=F4UV
-----END PGP SIGNATURE-----

--gj572EiMnwbLXET9--