From owner-freebsd-geom@FreeBSD.ORG Thu Dec 7 13:25:57 2006 Return-Path: X-Original-To: freebsd-geom@freebsd.org Delivered-To: freebsd-geom@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id A911D16A40F for ; Thu, 7 Dec 2006 13:25:57 +0000 (UTC) (envelope-from anderson@centtech.com) Received: from mh1.centtech.com (moat3.centtech.com [64.129.166.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id BEE1543CA3 for ; Thu, 7 Dec 2006 13:25:05 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from [10.177.171.220] (neutrino.centtech.com [10.177.171.220]) by mh1.centtech.com (8.13.8/8.13.8) with ESMTP id kB7DPjKR086302; Thu, 7 Dec 2006 07:25:46 -0600 (CST) (envelope-from anderson@centtech.com) Message-ID: <45781663.3060008@centtech.com> Date: Thu, 07 Dec 2006 07:25:55 -0600 From: Eric Anderson User-Agent: Thunderbird 1.5.0.7 (X11/20061015) MIME-Version: 1.0 To: Ivan Voras References: <20061201104955.GG9880@obiwan.tataz.chchile.org> <4575E597.1030306@centtech.com> <4575EDEA.7020206@fer.hr> In-Reply-To: <4575EDEA.7020206@fer.hr> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV 0.88.4/2300/Thu Dec 7 06:14:04 2006 on mh1.centtech.com X-Virus-Status: Clean Cc: freebsd-geom@freebsd.org Subject: Re: gsnapshot around ? 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: Thu, 07 Dec 2006 13:25:57 -0000 On 12/05/06 16:08, Ivan Voras wrote: > Eric Anderson wrote: > >> I've been thinking a bit about this for a while. It would be a great >> tool to have, certainly. Does anyone have any particular >> implementation ideas? > > It's actually not that hard to do. I really want the possibility to save > snapshot data in a file (as opposed to dumping it to another GEOM > device), and PJD had some file-muching kernel code so it's definitely > doable right now. > > I'm still waiting on a "hot-plug" insertion of GEOM classes in between > two classes to make it really usable for the common man :) I've been thinking about a layered approach, so the gsnapshot would create a 'layer', and all new writes would go to the layer. Then, there would be another class, to stack layers (kind of like unionfs, except for block devices) - so when you wanted to view the data on a snapshot, you would stack the layers how you wanted, and then see the data. Kind of like journaling, kind of like regular COW, etc, but a little more Unix-style-ish in the manner of a few building blocks that can be used in many ways, and stacked together to make something powerful. Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology An undefined problem has an infinite number of solutions. ------------------------------------------------------------------------