From owner-freebsd-questions@FreeBSD.ORG Wed Mar 3 13:57:31 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 955BB16A4CE for ; Wed, 3 Mar 2004 13:57:31 -0800 (PST) Received: from smtpout.mac.com (A17-250-248-46.apple.com [17.250.248.46]) by mx1.FreeBSD.org (Postfix) with ESMTP id 482F743D1F for ; Wed, 3 Mar 2004 13:57:31 -0800 (PST) (envelope-from cswiger@mac.com) Received: from mac.com (smtpin07-en2 [10.13.10.152]) by smtpout.mac.com (8.12.6/MantshX 2.0) with ESMTP id i23LvUHO019959; Wed, 3 Mar 2004 13:57:30 -0800 (PST) Received: from [10.1.1.193] ([199.103.21.225]) (authenticated bits=0) by mac.com (Xserve/smtpin07/MantshX 3.0) with ESMTP id i23LvTgv011980; Wed, 3 Mar 2004 13:57:30 -0800 (PST) In-Reply-To: <20040303222612.W39053@guldivar.globalwire.se> References: <40452715.5030304@mindcore.net> <200403031453.49069.danny@ricin.com> <20040303160658.GA32905@happy-idiot-talk.infracaninophile.co.uk> <20040303222612.W39053@guldivar.globalwire.se> Mime-Version: 1.0 (Apple Message framework v612) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: Charles Swiger Date: Wed, 3 Mar 2004 16:57:43 -0500 To: Stefan Cars X-Mailer: Apple Mail (2.612) cc: Free BSD Questions list Subject: Re: 1 processor vs. 2 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: Wed, 03 Mar 2004 21:57:31 -0000 On Mar 3, 2004, at 4:26 PM, Stefan Cars wrote: > Okey, but if you would compare RAID-1 on two disks compared to RAID-5 > on > three disks then ? What would be the faster ? RAID-1 will be about 50% faster than RAID-5 doing reads regardless of size, and will also be *much* faster doing small writes-- by a factor of 4, perhaps. [ There is a potential optimization for RAID-5 using very large writes-- ie, bigger than the RAID interleave size * (# of disks - 1)-- that might make it more comparable with RAID-1's performance, only I believe FreeBSD breaks up large I/O requests into 32K or so, thus there generally never is the potential to not read the data before writing. ] -- -Chuck