From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Watts Subject: Re: 1x 3ware controllers vs. 2x 3ware controllers Date: Fri, 30 Jul 2004 17:17:36 +0100 Sender: linux-raid-owner@vger.kernel.org Message-ID: <200407301717.36583.mrwatts@fast24.co.uk> References: <200407300815.18296.mrwatts@fast24.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline To: Marc Bevand Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids > Mark Watts wrote: > > With the performance issues I'm seeing with the 8506-4LP's I have, I > > wouldn't recommend them to anyone currently... > > > > The thread on LKML from a few days ago about mke2fs -j and 8506-4LP says > > it all, but basically and reasonable amount of I/O brings a Dual Opteron > > system to its knees. > > And by reasonable I mean copying ISO images from a usb2 drive to a raid 5 > > (4 x 250GB maxtor) or even just formatting a 600MB partition. > > I would be interested to see the output of 'vmstat 1' while your system is > so slow. > > IMHO you shouldn't draw such conclusion ("reasonable amount of I/O brings a > Dual Opteron system to its knees") from your particular case. The 3 HT > links of the Opteron make this CPU particularly adapted to I/O operations. Well its the only conclusion I *can* come to at this time. When you move from a UP 1.8Ghz P4 with single EIDE disks to SMP Opteron with 4 times the ram and a hardware raid card, you tend to assume that performance in all areas will go up. When it doesn't, and you find yourself watching screen redraws while you format a 600GB partition (ext3) you do feel the need to blame something :) I'm all ears for suggestions on what me be wrong or things I can try to improve performance. > > Personnaly, on a dual Opteron, I am able to read datas from 4 SATA disks at > about 225 MB/s, with CPU time used at about 32%, awd with a system still > reasonably responsive. I'm seeing ~80MB/sec reading from the 3ware raid-5 according to hdparm and bonnie++ Write performance is around 25MB/sec according to bonnie++. Mark.