On 01/02/2013 08:50 AM, Stefan Hajnoczi wrote: > On Tue, Dec 18, 2012 at 10:18:20AM -0000, Andy Menzel wrote: >> Any solution right now? I have a similar problem like Todor Andreev; >> Our daily backup of some virtual machines (qcow2) looks like that: >> >> 1. shutdown the VM >> 2. create a snapshot via: "qemu-img snapshot -c nameofsnapshot..." >> 3. boot the VM >> 4. backup the snapshot to another virtual disk via: "qemu-img convert -f >> qcow2 -O qcow2 -s nameofsnapshot..." >> 5. DELETE the snapshot from VM via: qemu-img snapshot -d nameofsnapshot... > > It's not safe to modify the qcow2 file while the guest is running. This > means Step 5 is not really safe and could result in an inconsistent > image. > > This may also be causing the problem: the QEMU process has a variable > with the next free cluster index. Since Step 5 runs as a separate > process it does not update the QEMU process' next free cluster index > variable. QEMU doesn't know that there are now free clusters within the > image file because you updated the file behind QEMU's back - the result > is that it grows the file. > > Please try deleting the last backup snapshot between Step 1 and Step 2. > This way you'll free the space while QEMU isn't accessing the image > file. When you boot up the image file again QEMU should reuse the freed > clusters.
You might also want to try modifying step 5 to use the HMP delvm monitor command from within the running qemu rather than going behind qemu's back with a qemu-img invocation. That's how libvirt deletes internal snapshots from a running qemu. Also, there are patches currently under review that are talking about creating a QMP counterpart to the delvm monitor command. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to qemu-kvm in Ubuntu. https://bugs.launchpad.net/bugs/1025244 Title: qcow2 image increasing disk size above the virtual limit To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1025244/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs
