From owner-freebsd-performance@FreeBSD.ORG Wed Sep 3 11:52:55 2003 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 870B416A4BF for ; Wed, 3 Sep 2003 11:52:55 -0700 (PDT) Received: from silver.he.iki.fi (helenius.fi [193.64.42.241]) by mx1.FreeBSD.org (Postfix) with ESMTP id 40F6743F85 for ; Wed, 3 Sep 2003 11:52:52 -0700 (PDT) (envelope-from pete@he.iki.fi) Received: from he.iki.fi (h81.vuokselantie10.fi [193.64.42.129]) by silver.he.iki.fi (8.12.9/8.11.4) with ESMTP id h83Iqo2k013124; Wed, 3 Sep 2003 21:52:50 +0300 (EEST) (envelope-from pete@he.iki.fi) Message-ID: <3F563881.70605@he.iki.fi> Date: Wed, 03 Sep 2003 21:52:49 +0300 From: Petri Helenius User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Piotr KUCHARSKI References: <3F5634FE.9080303@mac.com> <20030903184506.GC14797@sgh.waw.pl> In-Reply-To: <20030903184506.GC14797@sgh.waw.pl> Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 8bit cc: freebsd-performance@freebsd.org Subject: Re: 20TB Storage System (fsck????) X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Sep 2003 18:52:55 -0000 Piotr KUCHARSKI wrote: >How many is "too many"? Or, rather, what are write-performance penalties >when using sixteen disks in one hw raid5 set? (With two raid volumes, >2TB and 1.75TB available for OS.) > > With raid5 you read one and write two disks for each write, wide arrays really hurt when running on degraded mode but I donīt see whatīs the issue when running fully operational? Though people usually expect raid to deliver some performance when degraded so running raid50 instead of too wide raid5 is usually a good idea. (50 being striped raid5 arrays) Pete