From owner-freebsd-stable Sat Nov 23 19:22: 0 2002 Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DDA3B37B404 for ; Sat, 23 Nov 2002 19:21:58 -0800 (PST) Received: from mtiwmhc12.worldnet.att.net (mtiwmhc12.worldnet.att.net [204.127.131.116]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0A8EC43E6E for ; Sat, 23 Nov 2002 19:21:53 -0800 (PST) (envelope-from cswiger@mac.com) Received: from prime ([12.88.86.18]) by mtiwmhc12.worldnet.att.net (InterMail vM.5.01.05.12 201-253-122-126-112-20020820) with SMTP id <20021124032125.CLK13909.mtiwmhc12.worldnet.att.net@prime> for ; Sun, 24 Nov 2002 03:21:25 +0000 Message-ID: <01de01c29368$a2893ca0$0301a8c0@prime> From: "Charles Swiger" To: References: Subject: Re: RAID performance problems Date: Sat, 23 Nov 2002 22:21:52 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Pete French wrote: [ ... ] > 1) a 15k RPM drive attached directly to an Adaptec SCSI controller > 2) a RAID-1 mirrored pair of 10k RPS drives > 3) a RAID-5 set of 5 7200 RPM drives > > All SCSI buses are 40MB/sec. Both the RAID drives are being run from > the same Compaq 4200 RAID controller. Both the RAID controller and > the Adaptec SCSI card are on the same PCI bus. > > So, what I expected was that the driect drive would be fastest, > followed by the RAID-1, then the RAID-5 (at least as far as write > performance goes) You're not going to be able to derive firm conclusions from changing two variables at a time, unless you fill in the other missing pieces. Try comparing one of the five 7200 RPM drives via direct I/O versus two 7200 RPM drives in a RAID-1 mirror, versus the RAID-5 case. If you're using hardware RAID, then FreeBSD will be treating it like a single (larger) device, not going through vinum or some other OS-level software RAID. I agree that your results are somewhat surprising.... -Chuck To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message