From owner-freebsd-current@FreeBSD.ORG Mon Mar 31 18:55:52 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D7CA8106566B; Mon, 31 Mar 2008 18:55:52 +0000 (UTC) (envelope-from delphij@delphij.net) Received: from tarsier.delphij.net (delphij-pt.tunnel.tserv2.fmt.ipv6.he.net [IPv6:2001:470:1f03:2c9::2]) by mx1.freebsd.org (Postfix) with ESMTP id 7F8468FC28; Mon, 31 Mar 2008 18:55:52 +0000 (UTC) (envelope-from delphij@delphij.net) Received: from tarsier.geekcn.org (tarsier.geekcn.org [202.108.54.204]) (using TLSv1 with cipher ADH-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by tarsier.delphij.net (Postfix) with ESMTPS id 6C6DD28448; Tue, 1 Apr 2008 02:55:51 +0800 (CST) Received: from localhost (tarsier.geekcn.org [202.108.54.204]) by tarsier.geekcn.org (Postfix) with ESMTP id DC720EB92FE; Tue, 1 Apr 2008 02:55:50 +0800 (CST) X-Virus-Scanned: amavisd-new at geekcn.org Received: from tarsier.geekcn.org ([202.108.54.204]) by localhost (mail.geekcn.org [202.108.54.204]) (amavisd-new, port 10024) with ESMTP id G1Ci-CtG+Esp; Tue, 1 Apr 2008 02:55:45 +0800 (CST) Received: from charlie.delphij.net (71.5.7.139.ptr.us.xo.net [71.5.7.139]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by tarsier.geekcn.org (Postfix) with ESMTPSA id AF54BEB93C8; Tue, 1 Apr 2008 02:55:44 +0800 (CST) DomainKey-Signature: a=rsa-sha1; s=default; d=delphij.net; c=nofws; q=dns; h=message-id:date:from:reply-to:organization:user-agent: mime-version:to:cc:subject:references:in-reply-to: x-enigmail-version:openpgp:content-type:content-transfer-encoding; b=vR96jgk6MI0Gr3fgDzg8abDk84Bp8Sgwk+s/9d3q5jNHZwXgZOcbnK9C0CVAs9H3l loUz0ZsnnJ/AVHUOwz9qw== Message-ID: <47F133AE.2010900@delphij.net> Date: Mon, 31 Mar 2008 11:55:42 -0700 From: Xin LI Organization: The FreeBSD Project User-Agent: Thunderbird 2.0.0.12 (X11/20080312) MIME-Version: 1.0 To: Ivan Voras References: In-Reply-To: X-Enigmail-Version: 0.95.6 OpenPGP: id=18EDEBA0; url=http://www.delphij.net/delphij.asc Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-current@freebsd.org Subject: Re: Are large RAID stripe sizes useful with FreeBSD? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: d@delphij.net List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 31 Mar 2008 18:55:53 -0000 Ivan Voras wrote: > Most of new hardware RAID controllers offer stripe sizes of 128K, 256K > and some also have 512K and 1M stripes. In the simplest case of RAID0 of > two drives, knowing that the data is striped across the drives and that > FreeBSD issues IO request of at most 64K, is it useful to set stripe > sizes to anything larger than 32K? I suppose something like TCQ would > help the situation but does anyone know how is this situation usually > handled on the RAID controllers? Short answer: yes. Larger stripe sizes would allow better performance for continuous read/write. In theory they will negatively affect small size read/write but in practice you will notice that larger stripe size would give better performance in almost all cases. -- Xin LI http://www.delphij.net/ FreeBSD - The Power to Serve!