Hi, I performed the following: - 1. Shutdown VM. 2. Take a snapshot 3. Create a clone from snapshot. 4. Start the clone. Clone starts fine. 5. Attempt to delete snapshot from original VM, fails. 6. Attempt to start original VM, fails with "Bad volume specification". This was logged in VDSM during the snapshot deletion attempt. 2019-02-26 13:27:10,907+0000 ERROR (tasks/3) [storage.TaskManager.Task] (Task='67577e64-f29d-4c47-a38f-e54b905cae03') Unexpected error (task:872) Traceback (most recent call last):   File "/usr/share/vdsm/storage/task.py", line 879, in _run     return fn(*args, **kargs)   File "/usr/share/vdsm/storage/task.py", line 333, in run     return self.cmd(*self.argslist, **self.argsdict)   File "/usr/lib/python2.7/site-packages/vdsm/storage/securable.py", line 79, in wrapper     return method(self, *args, **kwargs)   File "/usr/share/vdsm/storage/sp.py", line 1892, in finalizeMerge     merge.finalize(subchainInfo)   File "/usr/share/vdsm/storage/merge.py", line 271, in finalize     optimal_size = subchain.base_vol.optimal_size()   File "/usr/share/vdsm/storage/blockVolume.py", line 440, in optimal_size     check = qemuimg.check(self.getVolumePath(), qemuimg.FORMAT.QCOW2)   File "/usr/lib/python2.7/site-packages/vdsm/qemuimg.py", line 157, in check     out = _run_cmd(cmd)   File "/usr/lib/python2.7/site-packages/vdsm/qemuimg.py", line 426, in _run_cmd     raise QImgError(cmd, rc, out, err) QImgError: cmd=['/usr/bin/qemu-img', 'check', '--output', 'json', '-f', 'qcow2', '/rhev/data-center/mnt/blockSD/024109d5-ea84-47ed-87e5-1c8681fdd177/images/f7dea7bd-04 6c-4923-b5a5-d0c1201607fc/ac540314-989d-42c2-9e7e-3907eedbe27f'], ecode=3, stdout={     "image-end-offset": 52210892800,     "total-clusters": 1638400,     "check-errors": 0,     "leaks": 323,     "leaks-fixed": 0,     "allocated-clusters": 795890,     "filename": "/rhev/data-center/mnt/blockSD/024109d5-ea84-47ed-87e5-1c8681fdd177/images/f7dea7bd-046c-4923-b5a5-d0c1201607fc/ac540314-989d-42c2-9e7e-3907eedbe27f",     "format": "qcow2",     "fragmented-clusters": 692941 } , stderr=Leaked cluster 81919 refcount=1 reference=0 Leaked cluster 81920 refcount=1 reference=0 Leaked cluster 81921 refcount=1 reference=0 etc.. Is there any way to fix these leaked clusters?  Running oVirt 4.1.9 with FC block storage. Thanks, Alan