From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Boylan Subject: Re: Best choice for copy/clone/snapshot Date: Wed, 13 May 2009 08:49:47 -0700 Message-ID: <1242229787.4004.9.camel@corn.betterworld.us> References: <1242176905.15140.38.camel@iron.psg.net> <4A0A71C0.1060109@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: ross@biostat.ucsf.edu, kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from upstrm185.psg-ucsf.org ([38.99.193.74]:8987 "EHLO biostat.ucsf.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754301AbZEMPtz (ORCPT ); Wed, 13 May 2009 11:49:55 -0400 In-Reply-To: <4A0A71C0.1060109@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Thanks for all the info. I have one follow up. On Wed, 2009-05-13 at 10:07 +0300, Avi Kivity wrote: > > > As I install software onto a system I want to preserve its > state--just > > the disk state---at various points so I can go back. What is the > best > > way to do this? > > > > LVM snapshots. Read up on the 'lvcreate -s' command and option. I may have been unclear. I meant as I install software on the VM. Since some of them are running Windows, they can't do LVM. I am running LVM on my host Linux system. Or are you suggesting that I put the image files on a snapshottable partition? Over time the snapshot seems likely to accumulate a lot of original sectors that don't involve the disk image I care about. Or do you mean I should back each virtual disk with an LVM volume? That does seem cleaner; I've just been following the docs and they use regular files. They say I can't just use a raw partition, but maybe kvm-img -f qcow2 /dev/MyVolumeGroup/Volume10 ? Does that give better performance? The one drawback I see is that I'd have to really take the space I wanted, rather than having it only notionally reserved for a file. I'm not sure how growing the logical volume would interact with qcow... Ross