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I am preparing at least one Windows 7 guest on a KVM Linux (ubuntu) host. I have made an LVM-based storage pool which I would like to use. My main concern is snapshots. The disk-image will be created on a logical volume, without all of qcow2's advanced features.

What is the best way to achieve (or approximate) snapshotting in this situation? Perhaps

  1. Use LVM snapshots.
  2. Use some other differential-backup tool.
  3. Somehow convince QEMU/KVM to keep the live filesystem on the logical volume but save the diffs (and RAM images) to a separate qcow2 file.

I think (3) would be the nicest, but some nasty intuition tells me it is not possible.

Scott Pack
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Adrian Ratnapala
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1 Answers1

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If you are going down the libvirt path why aren't you using the libvirt snapshot facility?

If you read the site you will see that it says:

Disk snapshots exist in two forms: internal (file formats such as qcow2 track both the snapshot and changes since the snapshot in a single file) and external (the snapshot is one file, and the changes since the snapshot are in another file).

Also

disk
This sub-element describes the snapshot properties of a specific disk. The attribute name is mandatory, and must match either the <target dev='name'/> ...

If your VM's disk is an LV you specify it using ...dev='lv_name'...

  • I thought it was limited to qcow2 and raw files i.e. that this was just libvirt's interface to whatever KVM offers. Are you saying that this actually offers functionality like (3). – Adrian Ratnapala Apr 18 '13 at 16:43