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+++ 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.
As Peter Krempa found out, this was caused by an incomplete backport for bug 1081032. The disksnapshot capability was only reported if the "blockdev-snapshot-sync" QMP commands was found, however in RHEL-6 we only probe for QMP commands on domain startup.
With qemu-kvm-rhev, virsh capabilities should report: <disksnapshot default='on' toggle='no'/> but not with qemu-kvm: <disksnapshot default='off' toggle='no'/>
Reproduce this with libvirt-0.10.2-46.el6.x86_64, verify with libvirt-0.10.2-47.el6.x86_64 1. with qemu-kvm-rhev + libvirt-0.10.2-46.el6.x86_64 1.1.# rpm -q libvirt qemu-kvm-rhev libvirt-0.10.2-46.el6.x86_64 qemu-kvm-rhev-0.12.1.2-2.448.el6.x86_64 1.2 # virsh -r capabilities |grep -i snapshot <disksnapshot default='off' toggle='no'/> <disksnapshot default='off' toggle='no'/> 2. with qemu-kvm + libvirt-0.10.2-46.el6.x86_64 2.1# rpm -q libvirt qemu-kvm libvirt-0.10.2-46.el6.x86_64 qemu-kvm-0.12.1.2-2.448.el6_6.x86_64 2.2 # virsh -r capabilities |grep -i snapshot <disksnapshot default='off' toggle='no'/> <disksnapshot default='off' toggle='no'/> 3. with qemu-kvm-rhev + libvirt-0.10.2-47.el6.x86_64 3.1# rpm -q libvirt qemu-kvm-rhev libvirt-0.10.2-47.el6.x86_64 qemu-kvm-rhev-0.12.1.2-2.448.el6.x86_64 3.2 # virsh -r capabilities |grep -i snapshot 4. with qemu-kvm + libvirt-0.10.2-47.el6.x86_64 4.1# rpm -q libvirt qemu-kvm-rhev libvirt-0.10.2-47.el6.x86_64 qemu-kvm-rhev-0.12.1.2-2.448.el6.x86_64 4.2 # virsh -r capabilities |grep -i snapshot
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHBA-2015-1252.html