On Wed, Jul 03, 2019 at 14:07:10 -0400, Roger Jin wrote:

Hi Libvirt, Is there a command that performs the same operation as blockpull while a domain is shutoff? I have a backing chain

base <-- A <-- B

that I would like to shorten to

base <-- B

Generally we refer as 'base' to the image which has overlays, so you are here describing a 'commit' operation. Which image is the topmost overlay used by the vm?

It seems like blockpull B, setting --base <path-to-base> does this, but only when the domain is running.

Libvirt currently does not implement these operations while the VM is shutoff because the difference of interactions beween qemu and qemu-img. As a workaround, you can either do the pull via qemu-img manually, or start the vm in paused mode (virsh start --paused), then do the blockpull and then 'virsh destroy' the VM. The filesystems would be never touched so 'destroy' should be safe in this case.