From owner-freebsd-current@FreeBSD.ORG Mon Oct 25 21:27:19 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5EAF616A4CF for ; Mon, 25 Oct 2004 21:27:19 +0000 (GMT) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id E99B943D4C for ; Mon, 25 Oct 2004 21:27:18 +0000 (GMT) (envelope-from scottl@freebsd.org) Received: from [192.168.254.11] (junior-wifi.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.12.11/8.12.10) with ESMTP id i9PLSE00077948; Mon, 25 Oct 2004 15:28:15 -0600 (MDT) (envelope-from scottl@freebsd.org) Message-ID: <417D6F4C.9000404@freebsd.org> Date: Mon, 25 Oct 2004 15:25:32 -0600 From: Scott Long User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.2) Gecko/20040929 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Brad Knowles References: <14479.1098695558@critter.freebsd.dk><417D25E8.6080804@ng.fadesa .es> <200410251928.01536.victor@alf.dyndns.ws><200410251837.58257.Thoma s.Sparrev ohn@btinternet.com><417D3F12.20302@DeepCore.dk> <417D40A1.9030802@ng.fadesa.es><417D45F1.9090504@freebsd.org> <77F3FD4D-26BE-11D9-9A2F-003065ABFD92@mac.com><417D58B6.5030509@fr eebsd.org > <417D65F1.2040809@freebsd.org> In-Reply-To: X-Enigmail-Version: 0.86.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=0.0 required=3.8 tests=none autolearn=no version=2.63 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on pooker.samsco.org cc: fandino@ng.fadesa.es cc: Charles Swiger cc: freebsd-current@freebsd.org Subject: Re: FreeBSD 5.3b7and poor ata performance X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 25 Oct 2004 21:27:19 -0000 Brad Knowles wrote: > At 2:45 PM -0600 2004-10-25, Scott Long wrote: > >> RAID-0 yes, RAID-10 no, at least not for software RAID. The machine >> winds up having to transfer the same data twice across the PCI bus, >> twice through the controller, etc. If the controller is on a simple >> PCI-32/33 bus then it will quickly become saturated. > > > I can't speak for GEOM, but my experience with vinum is that > software RAID, especially RAID-1+0 will totally smoke the bare hardware, > and will smoke most any PCI hardware RAID controller you put it up against. > > Granted, my experience is a few years old, so if you've got any more > recent data that shows in detail what the current situation is and > explains why, I'd love to see it. Until then, I stand by my results at > . > Software RAID does indeed have less latency than PCI RAID, and will often result in higher performance. But as was said, there is always a performance vs. reliability tradeoff. And when you are talking about RAID-10 with a bunch of disks, you will indeed start seeing bottlenecks in the bus. Scott