From owner-freebsd-geom@FreeBSD.ORG Mon Aug 28 16:47:15 2006 Return-Path: X-Original-To: freebsd-geom@freebsd.org Delivered-To: freebsd-geom@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A304816A4E0 for ; Mon, 28 Aug 2006 16:47:15 +0000 (UTC) (envelope-from anderson@centtech.com) Received: from mh1.centtech.com (moat3.centtech.com [207.200.51.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2EEAA43D66 for ; Mon, 28 Aug 2006 16:47:14 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from [10.177.171.220] (neutrino.centtech.com [10.177.171.220]) by mh1.centtech.com (8.13.1/8.13.1) with ESMTP id k7SGl4mu022753; Mon, 28 Aug 2006 11:47:05 -0500 (CDT) (envelope-from anderson@centtech.com) Message-ID: <44F31E07.4050008@centtech.com> Date: Mon, 28 Aug 2006 11:47:03 -0500 From: Eric Anderson User-Agent: Thunderbird 1.5.0.5 (X11/20060802) MIME-Version: 1.0 To: Christian Laursen References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV 0.87.1/1745/Mon Aug 28 10:02:21 2006 on mh1.centtech.com X-Virus-Status: Clean Cc: freebsd-geom@freebsd.org Subject: Re: Geom class project idea - geom_cow X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Aug 2006 16:47:15 -0000 On 08/28/06 11:37, Christian Laursen wrote: > I have an idea for a geom class that I think could be useful in a number > of scenarios. > > The basic idea is that it takes two existing providers and uses the first > one as a starting point and the other one to keep changes to the first > one using copy-on-write. > > The second provider will need a bitmap to keep track of the blocks that > have changed as well as at least as much space as the base provider. > > A number of the cases in which this class would prove useful are cases > where you would otherwise choose unionfs. However, approaching this > problem in geom seems simpler. (At least to me) > > I propose that this idea be added to > and/or . > > Unfortunately I don't have the time nor much kernel hacking experience to > do this myself at this point. > This sounds a little like the gjournal project done by Ivan Voras for last years SoC project. Does it seem like what you want? Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------