Re: Reopen qcow2 backing file from new location

[Alberto Garcia]

On Fri, Jun 23, 2023 at 11:50:10AM +0200, Stanislav Datskevych wrote:

> Unfortunately, change-backing-file only changes the string in the
> image's metadata and doesn't cause QEMU to reopen it on the running
> VM.  So in order to fully migrate VM to its new storage, the VM must
> be stopped and started.
> 
> Maybe there is a way to force qemu to reopen the backing file? 

I think that blockdev-reopen is what you are looking for:

   
https://www.qemu.org/docs/master/interop/qemu-storage-daemon-qmp-ref.html#qapidoc-780

It is option (3) from that list: first you open <new_backingfile_path>
using blockdev-add and then use blockdev-reopen to make 'backing'
point to this new backing file.

Berto