From owner-freebsd-questions@FreeBSD.ORG Sat Jan 24 20:25:08 2004 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8605E16A4CE for ; Sat, 24 Jan 2004 20:25:08 -0800 (PST) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id 740F343D1F for ; Sat, 24 Jan 2004 20:25:07 -0800 (PST) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.12.10/8.12.10) id i0P4P4Np022798; Sat, 24 Jan 2004 22:25:04 -0600 (CST) (envelope-from dan) Date: Sat, 24 Jan 2004 22:25:04 -0600 From: Dan Nelson To: Rishi Chopra Message-ID: <20040125042504.GC74242@dan.emsphone.com> References: <401207EF.7030005@cal.berkeley.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <401207EF.7030005@cal.berkeley.edu> X-OS: FreeBSD 5.2-CURRENT X-message-flag: Outlook Error User-Agent: Mutt/1.5.5.1i cc: questions@freebsd.org Subject: Re: Adaptec 2400A Performance X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Jan 2004 04:25:08 -0000 In the last episode (Jan 23), Rishi Chopra said: > I've run some imperical tests on the Adaptec 2400A raid controller > (results and setup can be seen here): > > http://www.ocf.berkeley.edu/~rchopra/RaidResults.html > > I was rather disappointed with the results. Can anyone suggest what > might be causing such slow disk speeds, or whether these speeds are > out of the ordinary for a 4-disk FreeBSD RAID5 installation? I have > done nothing to configure the card aside from striping the array in > BIOS; FreeBSD seems to automatically detect the disks. > > I once ran a 2-disk RAID-0 installation on Win2k which was 6-7 times > faster on sequential read/write tests (60-70MB/sec), hence my dismay. RAID-5 has to do 4 I/Os for every write, which would explain the bad write performance, but I can't explain your read performance. It's not strictly comparable, but a Raid-5 4x73gb SCSI setup using an Adaptec 3200S (128MB cache), which looks like it uses the same RAID engine and firmware as your 2400A, averages 18MB/sec writes and 50MB/sec reads. Your card configured with a RAID 0 volume should equal your w2k speeds. -- Dan Nelson dnelson@allantgroup.com