From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <506EAAD0.5040706@redhat.com> Date: Fri, 05 Oct 2012 10:39:28 +0100 From: "Bryn M. Reeves" MIME-Version: 1.0 References: <506C5CD8.2070502@mohawksoft.com> <506CFA0B.4000006@tlinx.org> <506D055E.901@mohawksoft.com> <506D1931.4040102@tlinx.org> <506D624A.5070104@mohawksoft.com> <506DA0B4.5020208@redhat.com> <506DA504.8010509@mohawksoft.com> <506E0701.1070103@bmsi.com> In-Reply-To: <506E0701.1070103@bmsi.com> Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] access or interface to list of blocks that have, changed via C.O.W.? Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii" To: LVM general discussion and development On 10/04/2012 11:00 PM, Stuart D Gathman wrote: > On 10/04/2012 11:02 AM, Mark Woodward expounded in part: >> >>> snapshot target and metadata format. It does not share code with >>> current (or historic afaik) LVM2/device-mapper and has been dead for a >>> number of years (last commits around 2008). >>> >>>> get the code. It old and not supported currently, but still works. >>>> I >>> Really? I'd be surprised if it even builds against modern kernels or >>> device-mapper. >> ddsnap was the Zumastor snapshot tool which uses a different in-kernel >> Well..... >> The LVM2 code that ships with most distros still uses the old >> interfaces and still (Ubuntu 12.04) seemst to create a COW file with SnAp > > This utility (ddsnap work alike) requires no kernel changes, and only > depends on the layout of the COW (and only on the changed block table): > > http://www.opensvc.com/init/default/doc_storage_dds This is closer to the kind of thing that Linda was originally asking about. It seems to let you extract deltas and move them around and re-apply them for replication purposes so it's similar to ddsnap in that it's distributed although as you say it's entirely in userspace and doesn't requite the ddsnap device-mapper target. Regards, Bryn.