snapshot-revert

KVM: creating and reverting libvirt external snapshots

Update July 2021: I have seen errors with external snapshots of volumes on versions of QEMU/KVM/libvirt from Ubuntu 20 Focal.  Adding note on using internal snapshot on volume backed by qcow2.   Internal snapshots created on QEMU copy-on-write (qcow2) disks are the most commonly used snapshot when using libvirt.  It is easy to see why; KVM: creating and reverting libvirt external snapshots