From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751744AbWCCWeh (ORCPT ); Fri, 3 Mar 2006 17:34:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751745AbWCCWeh (ORCPT ); Fri, 3 Mar 2006 17:34:37 -0500 Received: from e34.co.us.ibm.com ([32.97.110.152]:6581 "EHLO e34.co.us.ibm.com") by vger.kernel.org with ESMTP id S1750982AbWCCWeg (ORCPT ); Fri, 3 Mar 2006 17:34:36 -0500 From: Kevin Corry Organization: IBM To: linux-kernel@vger.kernel.org Subject: Re: is there a COW inside the kernel ? Date: Fri, 3 Mar 2006 16:39:58 -0600 User-Agent: KMail/1.8.3 Cc: "roland" References: <043101c63e9c$86e9d710$0200000a@aldipc> <200603030828.59567.kevcorry@us.ibm.com> <04cd01c63f09$a007a930$0200000a@aldipc> In-Reply-To: <04cd01c63f09$a007a930$0200000a@aldipc> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200603031639.58616.kevcorry@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri March 3 2006 3:29 pm, roland wrote: > i think i will take a closer look on device-mapper, but i'm unsure if it`s > perfectly suited. > > can i only use devices, not files for the cow? Yes, Device-Mapper can only map to block-devices. If you need to do this with files, you could use losetup to create block-device from them. However, the COW device still won't "grow" automatically as you described. > what about merging a cow-dev/file back to the r/o-dev/file ? Device-Mapper does not directly support this, but EVMS provides a "rollback" function for reverting an origin volume back to the contents of its snapshot volume. -- Kevin Corry kevcorry@us.ibm.com http://www.ibm.com/linux/ http://evms.sourceforge.net/