Create snapshot from volume and image-download results in size 0 in Red Hat OpenStack Platform

Issue

• Create snapshot from volume and image-download results in size 0 in Red Hat OpenStack Platform following this doc to migrate OpenStack instance: https://github.com/openstack/openstack-manuals/blob/stable/newton/doc/user-guide/source/cli-use-snapshots-to-migrate-instances.rst.

• Following the above procedure, snapshots are empty

For example:

• Shutdown instance

• Create snapshot

[stack@undercloud tmp]$ nova image-create --poll instance instance-backup
Server snapshotting... 100% complete
Finished

• Download the snapshot

[stack@undercloud tmp]$ glance image-download --file /tmp/instance.qcow2 <UUID>

• check the download image size

[stack@undercloud tmp]$ ls -la /tmp/instance.qcow2 
-rw-rw-r--. 1 stack stack 0 Jan 15 21:05 /tmp/instance.qcow2