Re: [Qemu-devel] [RFC] live snapshot, live merge, live block migration

[Stefan Hajnoczi]

I'm interested in what the API for snapshots would look like.
Specifically how does user software do the following:
1. Create a snapshot
2. Delete a snapshot
3. List snapshots
4. Access data from a snapshot
5. Restore a VM from a snapshot
6. Get the dirty blocks list (for incremental backup)

We've discussed image format-level approaches but I think the scope of
the API should cover several levels at which snapshots are
implemented:
1. Image format - image file snapshot (Jes, Jagane)
2. Host file system - ext4 and btrfs snapshots
3. Storage system - LVM or SAN volume snapshots

It will be hard to take advantage of more efficient host file system
or storage system snapshots if they are not designed in now.

Is anyone familiar enough with the libvirt storage APIs to draft an
extension that adds snapshot support?  I will take a stab at it if no
one else want to try it.

Stefan