Re: [libvirt-users] Create qcow2 v3 volumes via libvirt

On Wed, May 02, 2018 at 02:45:05PM +0200, Gionatan Danti wrote: Yes, you still have to clean up external snapshot metadata manually, as the link below indicates. Deleting external snapshots is a non-trivial problem. For example, if you have a disk image chain like: [A] <-- [B] <-- [C] <-- [D] Now if you no longer need image [B], what is the most efficient way to get rid of it? Three possibilities: - Merge [B] into [A], and rewrite the backing chain of [C] to point to [A]. Now can you discard image [B]. - Merge [A] into [B], call the new image [AB]. Now you can discard [A]. - Merge [B] into [C], and rewrite the backing chain of [C] to point to [A]. Now you can discard image [B]. It depends on how large each of the disk images are, and based on the size, merge / coalesce them accordingly, to arrive at the quickest solution. Note that existing commands (`virsh blockpull` and `virsh blockcommit`, which is relatively faster) will allow you handle it manually or script it -- which many people already do it. A couple of references (that are also easily scriptable): http://wiki.libvirt.org/page/Live-merge-an-entire-disk-image-chain-includ... https://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit I don't see any problem creation external snapshots (or more correctly: "overlays"). Deletion of external snapshots involves a bit more work, but it is scriptable as well. [...] -- /kashyap