OLVM: Snapshot Deletion Failed with "Failed to live merge. Top volume is still in qemu chain" (Doc ID 2758020.1)

Last updated on DECEMBER 26, 2023

Applies to:

Symptoms

Snapshot deletion failed when VM is running:

Engine.log:

2021-03-05 11:36:21,194+10 ERROR [org.ovirt.engine.core.bll.MergeStatusCommand] (EE-ManagedThreadFactory-commandCoordinator-Thread-2) [c1d69a15-3cc3-491b-99a9-ea1e4d09a5fb] Failed to live merge. 
Top volume 0e8a657b-32a8-4f50-862a-459de48158c6 is still in qemu chain [0e8a657b-32a8-4f50-862a-459de48158c6, 1b2569cf-1468-42d7-ab98-056009b754e6]
2021-03-05 11:36:22,172+10 ERROR [org.ovirt.engine.core.bll.snapshots.RemoveSnapshotSingleDiskLiveCommand] (EE-ManagedThreadFactory-engineScheduled-Thread-44) [c1d69a15-3cc3-491b-99a9-ea1e4d09a5fb] 
Command id: '0ab4493e-3278-4c73-b73f-74f68968669b failed child command status for step 'MERGE_STATUS'
2021-03-05 11:36:22,172+10 INFO [org.ovirt.engine.core.bll.snapshots.RemoveSnapshotSingleDiskLiveCommandCallback] (EE-ManagedThreadFactory-engineScheduled-Thread-44) [c1d69a15-3cc3-491b-99a9-ea1e4d09a5fb] 
Command 'RemoveSnapshotSingleDiskLive' id: '0ab4493e-3278-4c73-b73f-74f68968669b' child commands '[59de3f64-e484-4d24-8f1b-3b64286ebab6, 47ab6d86-3f5e-41a0-be6b-3f649405a2fb, a2f8b740-c24e-4ca6-b4bd-d604708f32c7]' 
executions were completed, status 'FAILED'
...
2021-03-05 11:36:23,309+10 ERROR [org.ovirt.engine.core.bll.snapshots.RemoveSnapshotSingleDiskLiveCommand] (EE-ManagedThreadFactory-engineScheduled-Thread-26) [c1d69a15-3cc3-491b-99a9-ea1e4d09a5fb] 
Merging of snapshot 'e9fa86fa-0799-48a0-9fef-a9a6bfe9a095' images '1b2569cf-1468-42d7-ab98-056009b754e6'..'0e8a657b-32a8-4f50-862a-459de48158c6' failed. Images have been marked illegal and can no 
longer be previewed or reverted to. Please retry Live Merge on the snapshot to complete the operation.
2021-03-05 11:36:23,313+10 ERROR [org.ovirt.engine.core.bll.snapshots.RemoveSnapshotSingleDiskLiveCommand] (EE-ManagedThreadFactory-engineScheduled-Thread-26) [c1d69a15-3cc3-491b-99a9-ea1e4d09a5fb] 
Ending command 'org.ovirt.engine.core.bll.snapshots.RemoveSnapshotSingleDiskLiveCommand' with failure.

vdsm.log:

2021-03-05 11:35:50,084+1000 INFO (jsonrpc/1) [virt.vm] (vmId='b190887c-7f29-4d97-8b24-0bc508b0049a') Starting merge with jobUUID=u'd3f75a5f-34f5-4c1d-8417-3619cac92a3b',
original chain=1b2569cf-1468-42d7-ab98-056009b754e6 < 0e8a657b-32a8-4f50-862a-459de48158c6 (top), disk='sdb', base='sdb[1]', top=None, bandwidth=0, flags=12 (vm:5951)
2021-03-05 11:35:50,091+1000 ERROR (jsonrpc/1) [virt.vm] (vmId='b190887c-7f29-4d97-8b24-0bc508b0049a') Live merge failed (job: d3f75a5f-34f5-4c1d-8417-3619cac92a3b) (vm:59
57)
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: internal error: qemu block name 'json:{"backing": {"driver": "raw", "file": {"driver": "file", "filename": "/rhev/data-center/mnt/_okvmdata_images/8747066c-2
85e-4adf-a067-0b29f290f19a/images/12c4efff-79c9-4120-b331-623868a7886b/1b2569cf-1468-42d7-ab98-056009b754e6"}}, "driver": "qcow2", "file": {"driver": "file", "filename": "
/rhev/data-center/mnt/_okvmdata_images/8747066c-285e-4adf-a067-0b29f290f19a/images/12c4efff-79c9-4120-b331-623868a7886b/0e8a657b-32a8-4f50-862a-459de48158c6"}}' doesn't ma
tch expected '/rhev/data-center/mnt/_okvmdata_images/8747066c-285e-4adf-a067-0b29f290f19a/images/12c4efff-79c9-4120-b331-623868a7886b/0e8a657b-32a8-4f50-862a-459de48158c6'
2021-03-05 11:35:50,101+1000 INFO (jsonrpc/1) [api.virt] FINISH merge return={'status': {'message': 'Merge failed', 'code': 52}} from=::ffff:192.168.51.65,38199, flow_id=
c1d69a15-3cc3-491b-99a9-ea1e4d09a5fb, vmId=b190887c-7f29-4d97-8b24-0bc508b0049a (api:54)
2021-03-05 11:35:50,102+1000 INFO (jsonrpc/1) [jsonrpc.JsonRpcServer] RPC call VM.merge failed (error 52) in 0.05 seconds (__init__:312)

Cause

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