Bug 717869

Summary: virsh vol-clone drop the snapshot of qcow2 image
Product: [Community] Virtualization Tools Reporter: Huang Wenlong <whuang>
Component: libvirtAssignee: Eric Blake <eblake>
Status: CLOSED DEFERRED QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: crobinso, cwei, dyuan, mzhan, rbalakri, shyu
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Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2016-03-23 13:02:34 UTC Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Huang Wenlong 2011-06-30 08:52:19 UTC 
Description of problem:
virsh vol-clone drop the internal snapshot of qcow2 image


Version-Release number of selected component (if applicable):

libvirt-0.9.2-1.el6.x86_64
qemu-kvm-0.12.1.2-2.165.el6.x86_64
kernel-2.6.32-156.el6.x86_64
virt-manager-0.8.6-4.el6

How reproducible:
100%

Steps to Reproduce:
1)
#virsh snapshot-list snap-test
 Name                 Creation Time             State
---------------------------------------------------
2)
#virsh snapshot-create snap-test 
Domain snapshot 1309419977 created

3)
# virsh snapshot-list snap-test
 Name                 Creation Time             State
---------------------------------------------------
 1309419977           2011-06-30 15:46:17 +0800 running

4)
# virsh shutdown snap-test
Domain snap-test is being shutdown
5)
# virsh vol-clone /var/lib/libvirt/images/clone-2.qcow2  snap-test.qcow2
Vol snap-test.qcow2 cloned from clone-2.qcow2
6)
#qemu-img info snap-test.qcow2
image: snap-test.qcow2
file format: qcow2
virtual size: 8.0G (8589934592 bytes)
disk size: 4.2G
cluster_size: 65536

  
Actual results:
no snapshot

Expected results:
image still have the snapshot

Additional info:
after vol-clone  check the source image still has the snapshot

# qemu-img info clone-2.qcow2
image: clone-2.qcow2
file format: qcow2
virtual size: 8.0G (8589934592 bytes)
disk size: 4.7G
cluster_size: 65536
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         1309419977             491M 2011-06-30 15:46:17   00:05:00.995
Comment 2 Osier Yang 2011-07-04 09:04:43 UTC 
It's not dropped by "vol-clone", the storage driver doesn't have any stuff related to snapshot, means it even doesn't support management of volume snapshot in storage driver.

What you see snap-* in virsh is implemented by underlying hypervisor driver, currently, only ESX, VBOX, and QEMU driver support it, what libvirt does is sending request to the hypervisor for snapshot management.

Agree that it might help if probing the snapshot of volume, and support it in volume def in storage driver, though.
Comment 6 Cole Robinson 2016-03-23 13:02:34 UTC 
yeah this is really something that should be handled by a higher level cloning tool or API, this isn't vol-clone's fault