From owner-freebsd-questions@FreeBSD.ORG Fri Aug 3 16:33:31 2007 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D8C3216A417 for ; Fri, 3 Aug 2007 16:33:31 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.freebsd.org (Postfix) with ESMTP id AE25F13C481 for ; Fri, 3 Aug 2007 16:33:31 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id D73ED5DD8; Fri, 3 Aug 2007 12:33:30 -0400 (EDT) X-Virus-Scanned: amavisd-new at codefab.com Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Ia-c7kL3DkFe; Fri, 3 Aug 2007 12:33:27 -0400 (EDT) Received: from [192.168.1.3] (pool-96-224-41-41.nycmny.east.verizon.net [96.224.41.41]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by pi.codefab.com (Postfix) with ESMTP id 9BB885C67; Fri, 3 Aug 2007 12:33:27 -0400 (EDT) Message-ID: <46B358CC.8010804@mac.com> Date: Fri, 03 Aug 2007 12:33:16 -0400 From: Chuck Swiger User-Agent: Thunderbird 1.5.0.12 (Windows/20070509) MIME-Version: 1.0 To: Wojciech Puchar References: <20070803145528.B16127@wojtek.tensor.gdynia.pl> In-Reply-To: <20070803145528.B16127@wojtek.tensor.gdynia.pl> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: UFS and spreading data X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 03 Aug 2007 16:33:31 -0000 Wojciech Puchar wrote: > AFAIK UFS try to spread data quite evenly on disk to different cylinder > group - for large files, so small files can get it's space near inodes > etc.. Yes, UFS leaves some free space in each cylinder group if it can so that it can grow (especially small) files locally; big files will get spread across cylinder groups as a result. > but i would like to clear things up: > > i will set up say 3 disks with gconcat and make one partition for all > data on it. then i will populate it with all things and use it. > > will the data be quite spread on disks, so accesses to different things > could be done in parallel to 3 disks, or will it rather use space on one > disk first, then on second then on third. > > i'm asking about it as i prefer gconcat over gstripe as i can add more > disks to gconcat and do growfs then making system EASILY expandable. Using a stripe is going to give reliably-balanced I/O load to the underlying physical disks. If the concat is mostly empty, then no, I/O won't be evenly balanced. If you mostly fill it up and are doing multithreaded I/O to lots of files scattered all around, than concat should be OK. -- -Chuck