From owner-freebsd-performance@FreeBSD.ORG Mon Oct 30 07:05:33 2006 Return-Path: X-Original-To: performance@freebsd.org 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 F1AB416A40F for ; Mon, 30 Oct 2006 07:05:33 +0000 (UTC) (envelope-from arne_woerner@yahoo.com) Received: from web30309.mail.mud.yahoo.com (web30309.mail.mud.yahoo.com [209.191.69.71]) by mx1.FreeBSD.org (Postfix) with SMTP id 76EB443D55 for ; Mon, 30 Oct 2006 07:05:33 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: (qmail 5497 invoked by uid 60001); 30 Oct 2006 07:05:32 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:Received:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=AMTuyXRl7hnVMy2acVnByDac81FVHd/jd8fEeNYI4Gi1/OelGadM5MK+0S/sS+BMYp1Zie9HKk0IcOUKVFpzrXJRA4adtbaix9I66Q2qsHWuznhn01hpfb44rvDS8Ch3JPHj/ocO863zOIJ7w5yH1eIJBVpWi4VEb0rIpDsz3i8= ; Message-ID: <20061030070532.5495.qmail@web30309.mail.mud.yahoo.com> Received: from [213.54.132.43] by web30309.mail.mud.yahoo.com via HTTP; Sun, 29 Oct 2006 23:05:32 PST Date: Sun, 29 Oct 2006 23:05:32 -0800 (PST) From: "R. B. Riddick" To: performance@freebsd.org In-Reply-To: <20061030051913.GG1052@wantadilla.lemis.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: Subject: Re: gvinum raid5 performance seems slow X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Oct 2006 07:05:34 -0000 --- Greg 'groggy' Lehey wrote: > "Sufficiently large data blocks" equates to several megabytes. > Currently MAXPHYS, the largest transfer request that would get to the > bio layer, is 131072 bytes. This would imply a stripe size of not > more than 32 kB for a five disk array, which is unrealistically small. > > I did consider this optimization, but it would only work if Vinum were > first to buffer multiple requests, and there are all sorts of > reliability issues there. For example, you'd have to lie about the > first few requests that were only buffered and not actually sent out > to disk. Possibly it should be done anyway. > I did it that way in my graid5 class: http://home.tiscali.de/cmdr_faako/geom_raid5.tbz The source might look somehow incomprehensible, but it seems to be quite stable (on amd64 and i386)... I tried to benchmark with a 3 disk array: Single disk: 30MB/sec write speed graid5 device: 20MB/sec write speed I would be interested in other benchmarks about it. -Arne ____________________________________________________________________________________ Get your email and see which of your friends are online - Right on the New Yahoo.com (http://www.yahoo.com/preview)