OLVM: Snapshot Deletion Fails (live merge) after VM migration (Doc ID 2795975.1)

Last updated on NOVEMBER 17, 2021

Applies to:

Symptoms

Deletion of a snapshot in a running VM after the VM has been migrated to another host fails with the following message:
libvirtError: Requested operation is not valid: can't keep relative backing relationship

-- from /var/log/vdsm/vdsm.log:
Traceback (most recent call last):
File "/usr/lib/python2.7/site-packages/vdsm/virt/vm.py", line 5955, in merge
bandwidth, flags)
File "/usr/lib/python2.7/site-packages/vdsm/virt/virdomain.py", line 100, in f
ret = attr(*args, **kwargs)
File "/usr/lib/python2.7/site-packages/vdsm/common/libvirtconnection.py", line 131, in wrapper
ret = f(*args, **kwargs)
File "/usr/lib/python2.7/site-packages/vdsm/common/function.py", line 94, in wrapper
return func(inst, *args, **kwargs)
File "/usr/lib64/python2.7/site-packages/libvirt.py", line 719, in blockCommit
if ret == -1: raise libvirtError ('virDomainBlockCommit() failed', dom=self)
libvirtError: Requested operation is not valid: can't keep relative backing relationship

Note that creating and deleting a snapshot while the VM is running in the same Hypervisor leads to no errors.
The problem only occurs if a snapshot is taken then the VM is migrated to another Hypervisor.

Changes

The libvirt version installed in the Hypervisors <= 5.7.0-28.

Cause

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