On Sat, Apr 22, 2017 at 11:26:17PM -0500, Leroy Tennison wrote:

I have used

virsh snapshot-create-as <VM name> <snapshot name> "<snapshot description>" --diskspec "vda,snapshot=external,file=/path/to/external-snapshot" --disk-only --atomic

To avoid creating libvirt metadata for external snapshots, here you can provide the option '--no-metadata' to `virsh snapshot-create-as` so that libvirt won't track the metadata anymore. This avoids having to delete it manually (which you can do as I outlined further down below).

to create an external snapshot of a running VM. I followed it with

virsh blockpull <VM name> --path /path/to/external-snapshot

Slightly related: `blockcommit` is relatively faster than `blockpull` in this case -- because your base image ("original-image-file.qcow") should have the bulk of the content, so `blockcommit` will copy only the _delta_ from the original, which was stored in your 'external-snapshot.qcow2', so it'll be a shorter copy operation. Here's some notes related to it: http://wiki.libvirt.org/page/Live-disk-backup-with-active-blockcommit

and monitored it until done. I confirmed it with

qemu-img info /path/to/external-snapshot

which shows no backing store.

However, when I do

grep {/etc,/run}/libvirt/qemu/<VM name>.xml

the xml for the VM still shows a backing store in the /run/... definition (but not in the /etc/... definition, my understanding is that the /etc/... definition won't be updated until the VM is shut down):

<disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/var/lib/libvirt/images/external-snapshot.qcow2'/> <backingStore type='file' index='1'> <format type='qcow2'/> <source file='/var/lib/libvirt/images/original-image-file.qcow'/> <backingStore/> </backingStore> <target dev='hda' bus='ide'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk>

This is using libvirtd version 1.3.1 and qemu-img version 2.5.0.

How do I resolve this situation? I don't want to have to rely on a backing store permanently. Thanks for any help or pointers.

You can look at the existing snapshot metadata libvirt is tracking: $ virsh snapshot-list --tree vm1 And then delete the metadata (the below command does that) for a named snapshot: $ virsh snapshot-delete vm1 --metadata snap1 -- /kashyap