On Oct 15, 2013, at 3:46 PM, Richard W.M. Jones <rjones@xxxxxxxxxx> wrote: > On Tue, Oct 15, 2013 at 03:29:38PM -0600, Chris Murphy wrote: >> The better snapshots sound ideal for VM testing. Snapshot a >> successful install and then try to break the snapshot. Etc. >> >> Presently virt-manager ignores thinp pools and only creates >> conventional LV's. I haven't tried using virsh to force it to use an >> already created virtualsize LV as backing, but I'm wondering if it >> should work. If not, is there a rough time frame on such support? > > Is using LVs for this over-thinking things? Could be. > Creating a snapshot of a regular file which efficiently shares the > backing disk is easy, and doesn't require root or special support: > > qemu-img create -f qcow2 -b original snapshot.qcow2 Yes but unallocated qcow2 is slower than either kind of LV. And it's noticeable when doing something like guest using XFS in a qcow2 file on btrfs host, or guest using btrfs in a qcow2 file on btrfs host. It's double the file system activity. On an LV there's pretty close to no hit. I'm happy to hear it argued I should instead use the LV space for a regular partition formatted ext2 and drop the qcow2 file there. There's still overhead of two file systems there, but may compare to LV performance. > > Then you can import this as a new guest in libvirt, again *without* > needing root: > > virt-install --import --name snapshot \ > --ram 1024 --disk path=snapshot.qcow2,format=qcow2 > > And in Fedora 20 we'll have virt-builder, which makes creating the > original images quick too. (Not to mention virt-sysprep and all the > other tools to manipulate disk images easily, without root) Hmm good to know. Chris Murphy -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
