From owner-freebsd-performance@FreeBSD.ORG Fri Feb 20 11:35:18 2004 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 7362316A4CE for ; Fri, 20 Feb 2004 11:35:18 -0800 (PST) Received: from mail.webjockey.net (mail.webjockey.net [208.141.46.3]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2B7DF43D1F for ; Fri, 20 Feb 2004 11:35:18 -0800 (PST) (envelope-from gary@outloud.org) Received: from uranium-xkzwf96.outloud.org (69-160-74-173.frdrmd.adelphia.net [69.160.74.173]) by mail.webjockey.net (8.12.10/8.12.8) with ESMTP id i1KJZb8O053762; Fri, 20 Feb 2004 14:35:37 -0500 (EST) (envelope-from gary@outloud.org) Message-Id: <6.0.1.1.2.20040220143227.01ee0ec0@208.141.46.3> X-Sender: ancient@208.141.46.3 X-Mailer: QUALCOMM Windows Eudora Version 6.0.1.1 Date: Fri, 20 Feb 2004 14:35:25 -0500 To: Charles Swiger From: Gary Stanley In-Reply-To: References: <200402181729.06202@misha-mx.virtual-estates.net> <20040220072258.GA17579@VARK.homeunix.com> <200402201147.03606@misha-mx.virtual-estates.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed cc: freebsd-performance@freebsd.org Subject: Re: strange performance dip shown by iozone 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: Fri, 20 Feb 2004 19:35:18 -0000 Here's some knobs to try, ie; RAID5: Write Back Cache, Normal Read Ahead, and Direct I/O RAID1: Write Through Cache, Normal Read Ahead, and Direct I/O That picked up my write speeds just enough so it wasn't nearly as bad writing as reading. At 02:27 PM 2/20/2004, you wrote: >On Feb 20, 2004, at 11:47 AM, mi+mx@aldan.algebra.com wrote: >>Also, is the RAID5 writing speed supposed to be _so much_ worse, than >>that of a single disk? > >it's normal for RAID-5 write performance to be slower than that of a bare >drive. RAID filesystems involve tradeoffs between cost, performance, and >reliability. RAID-5 maximizes cost and reliability at the expense of >performance.... > >-- >-Chuck > >_______________________________________________ >freebsd-performance@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-performance >To unsubscribe, send any mail to "freebsd-performance-unsubscribe@freebsd.org"