Bug 1149667

+++ This bug was initially created as a clone of Bug #1149460 +++

Description of problem:
rhel-guest-image-7.0-20140930.0.el7 snapshot fails while running over couple of RHEL6.6.

Version-Release number of selected component (if applicable):
libvirt-client-0.10.2-46.el6.x86_64
libvirt-0.10.2-46.el6.x86_64
libvirt-python-0.10.2-46.el6.x86_64
libvirt-lock-sanlock-0.10.2-46.el6.x86_64
qemu-kvm-rhev-0.12.1.2-2.448.el6.x86_64
vdsm-4.16.5-2.el6ev.x86_64
sanlock-2.8-1.el6.x86_64


How reproducible:
100%

Steps to Reproduce:
1.First of all you have to disable selinux on both your RHEL6.6 hosts with setenforce 0.
2.Now try executing live snapshot from running guest-image VM on some RHEL6.6 host.
3.Snapshhot, fails...

Actual results:
PSA (please see attachments).

Expected results:
Snapshot should pass.

Additional info:
logs attached.

--- Additional comment from Francesco Romani on 2014-10-06 05:31:09 EDT ---


I checked locally on the box (in read only mode, so no harm is possible).

VDSM indeed reports that live snapshot is not supported. This causes the engine to prohibit the operation as shown. This is expected and the wanted behaviour.

# vdsClient -s 0 getVdsCaps | grep -i snapshot
	liveSnapshot = 'false'

However, VDSM is acting as middleman here. Let's check what libvirt reports:

# virsh -r capabilities | grep -i snapshot
      <disksnapshot default='off' toggle='no'/>
      <disksnapshot default='off' toggle='no'/>

And this is the reason why it fails.
Now, that's either libvirt or qemu issue.

--- Additional comment from Francesco Romani on 2014-10-06 05:38:12 EDT ---

Seems libvirt issue.

Still on the affected box:

# telnet localhost 4444
Trying ::1...
Connected to localhost.
Escape character is '^]'.
{"QMP": {"version": {"qemu": {"micro": 1, "minor": 12, "major": 0}, "package": "(qemu-kvm-rhev-0.12.1.2-2.448.el6)"}, "capabilities": []}}
{ "execute": "qmp_capabilities" }
{"return": {}}
{ "execute": "query-commands" }
{"return": [{"name": "quit"}, {"name": "eject"}, {"name": "__com.redhat_drive_del"}, {"name": "change"}, {"name": "screendump"}, {"name": "__com.redhat_qxl_screendump"}, {"name": "stop"}, {"name": "cont"}, {"name": "system_wakeup"}, {"name": "system_reset"}, {"name": "system_powerdown"}, {"name": "device_add"}, {"name": "device_del"}, {"name": "cpu"}, {"name": "memsave"}, {"name": "pmemsave"}, {"name": "inject-nmi"}, {"name": "migrate"}, {"name": "migrate_cancel"}, {"name": "migrate_set_speed"}, {"name": "client_migrate_info"}, {"name": "dump-guest-memory"}, {"name": "query-dump-guest-memory-capability"}, {"name": "migrate_set_downtime"}, {"name": "block_resize"}, {"name": "netdev_add"}, {"name": "netdev_del"}, {"name": "transaction"}, {"name": "blockdev-snapshot-sync"}, {"name": "__com.redhat_drive-mirror"}, {"name": "__com.redhat_drive-reopen"}, {"name": "balloon"}, {"name": "set_link"}, {"name": "getfd"}, {"name": "closefd"}, {"name": "block_passwd"}, {"name": "block_set_io_throttle"}, {"name": "set_password"}, {"name": "expire_password"}, {"name": "__com.redhat_set_password"}, {"name": "__com.redhat_spice_migrate_info"}, {"name": "qmp_capabilities"}, {"name": "human-monitor-command"}, {"name": "__com.redhat_drive_add"}, {"name": "block-stream"}, {"name": "__com.redhat_block-commit"}, {"name": "block-job-set-speed"}, {"name": "block-job-cancel"}, {"name": "chardev-add"}, {"name": "chardev-remove"}, {"name": "query-events"}, {"name": "query-pci"}, {"name": "query-version"}, {"name": "query-commands"}, {"name": "query-chardev"}, {"name": "query-block"}, {"name": "query-blockstats"}, {"name": "query-cpus"}, {"name": "query-kvm"}, {"name": "query-status"}, {"name": "query-mice"}, {"name": "query-vnc"}, {"name": "query-spice"}, {"name": "query-name"}, {"name": "query-uuid"}, {"name": "query-migrate"}, {"name": "query-balloon"}, {"name": "query-block-jobs"}]}

"blockdev-snapshot-sync" command is reported, thus the disk snapshot should be advertised as supported.