From owner-freebsd-performance@FreeBSD.ORG Thu Apr 28 15:59:08 2005 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 6F17816A4CE for ; Thu, 28 Apr 2005 15:59:08 +0000 (GMT) Received: from web41201.mail.yahoo.com (web41201.mail.yahoo.com [66.218.93.34]) by mx1.FreeBSD.org (Postfix) with SMTP id 3949F43D46 for ; Thu, 28 Apr 2005 15:59:08 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: (qmail 41483 invoked by uid 60001); 28 Apr 2005 15:59:08 -0000 Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; b=6dxqVCndG5fafemVL5TF/ZGaZKw3JIjLrMjVtUyEJgzo3XigWNzXX/jp77NuHfbOtWQvq1q+Z+bciVzobgEqLd8rhO/n/XfAnDYXhfiDeBYaHhc5h3W56LM1HXKZstB46167jFlMTr2J6rza+pxe5jVKkrL64dfkaRxeD9RAW9c= ; Message-ID: <20050428155908.41481.qmail@web41201.mail.yahoo.com> Received: from [83.129.189.236] by web41201.mail.yahoo.com via HTTP; Thu, 28 Apr 2005 08:59:07 PDT Date: Thu, 28 Apr 2005 08:59:07 -0700 (PDT) From: Arne "Wörner" To: Eric Anderson In-Reply-To: <4270F648.5030501@centtech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii cc: freebsd-performance@freebsd.org Subject: Re: Very low disk performance Highpoint 1820a 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: Thu, 28 Apr 2005 15:59:08 -0000 --- Eric Anderson wrote: > First, understand that RAID 5 is dependant on fast hardware to > performa > the XOR operations. A single disk without any RAID can easily > outperform a RAID array if the RAID array is on a 'slow' > controller. > The Highpoint controllers are not exactly high-end fast RAID > controllers, so ~50MB/s isn't too bad for that I would say. > Did you happen to try a vinum RAID5? How about a stripe? > Furthermore RAID-5 needs to read the parity block, before it can update that block, so that there are 2 disc transactions more, which could explain the better performance of a single disk, too? Or does the striping effect (inherent to RAID-5) compensate those 2 extra transactions (at least in case of sequential writes)? -Arne __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com