From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m54EvagJ016424 for ; Wed, 4 Jun 2008 10:57:36 -0400 Received: from mail.terrascale.net ([64.254.245.115]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id m54EvKfo029862 for ; Wed, 4 Jun 2008 10:57:20 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.terrascale.net (Postfix) with ESMTP id 776214B843F for ; Wed, 4 Jun 2008 10:02:00 -0400 (EDT) Received: from mail.terrascale.net ([127.0.0.1]) by localhost (andrei2.ts [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ABPnzNNwuZaG for ; Wed, 4 Jun 2008 10:01:57 -0400 (EDT) Received: from monkey.ts (monkey.ts [172.20.6.11]) by mail.terrascale.net (Postfix) with ESMTP id DC5064B843D for ; Wed, 4 Jun 2008 10:01:54 -0400 (EDT) Message-ID: <4846A052.10607@rackable.com> Date: Wed, 04 Jun 2008 10:01:54 -0400 From: Steeve McCauley MIME-Version: 1.0 Subject: Re: [linux-lvm] ANNOUNCE: an experimental implementation of snapshot merging References: In-Reply-To: Content-Transfer-Encoding: 7bit Reply-To: steeve@terrascale.net, 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"; format="flowed" To: LVM general discussion and development Is this change meant to add cluster support for merging? I had been under the assumption that merging was already a feature of snapshots. What is the difference between the current implementation using lvremove (which I assumed was where the COW blocks were merged back into the original volume) and lvconvert as below? Why was this functionality not kept in lvremove? Mikulas Patocka wrote: > Hi > > Here I release the first experimental implementation of snapshot > merging. Merging allows you to copy data in snapshot back to the origin > device. Once merging starts, it runs on background. When the merging > finishes (you see "0%" with "lvs" command), you should remove the > merging snapshot with lvremove command. > > The userspace will still be changed, the kernel is already finished > (there are no known bugs in the kernel, I'm curious about the unknown > ones :) > > Merging is initiated with "lvconvert -M vg/lv_snapshot" command. When > you initiate merging, make sure that the origin device is not mounted. > Snapshot can be mounted while it's merging is initiated. > > During merging, aby reads and writes to the origin device are identical > to accesses to the merging snapshots. > > There may be multiple snapshots while one of them is being merged --- > exceptions in other snapshots are being allocated and there snapshots > are kept stable. > > Don't try to concurrently merge more than one snapshot (the kernel > refuses to do it, the userspace tools don't know about it --- the > userspace will be rewritten anyway). > > The patches are at: > http://people.redhat.com/mpatocka/patches/ > The patches are for 2.6.26-rc4 > > (besides merging, there are some other bugfixes, I made for the kernel) > > Mikulas > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ -- Steeve McCauley Director of Research and Development Rackable Systems 407 McGill Street, Suite 1002 Montreal, Quebec, H2Y 2G3 (Canada) Tel: 514-288-3343 http://www.rackable.com :wq