[libvirt-users] Creating a snapshot from a KVM VM fails
Hi, I'm trying to create a snapshot from a KVM VM: # virsh snapshot-create one-5 error: unsupported configuration: internal checkpoints require at least one disk to be selected for snapshot How can I debug this error message and what does it mean? Some system information: * Ubuntu 13.04 64Bit * virsh --version: 1.0.2 * The XML of the VM is below Thanks for all help... Cheers, Tobias <domain type='kvm' id='4'> <name>one-5</name> <uuid>cff38c6a-2996-7709-c4f4-0ed826c2fb02</uuid> <memory unit='KiB'>524288</memory> <currentMemory unit='KiB'>524288</currentMemory> <vcpu placement='static'>1</vcpu> <cputune> <shares>1024</shares> </cputune> <os> <type arch='x86_64' machine='pc-i440fx-1.4'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <devices> <emulator>/usr/bin/kvm</emulator> <disk type='network' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source protocol='rbd' name='one/one-5-5-0'/> <target dev='hda' bus='ide'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk> <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <source file='/var/lib/one//datastores/0/5/disk.1'/> <target dev='hdb' bus='ide'/> <readonly/> <alias name='ide0-0-1'/> <address type='drive' controller='0' bus='0' target='0' unit='1'/> </disk> <controller type='ide' index='0'> <alias name='ide0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <controller type='usb' index='0'> <alias name='usb0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/> </controller> <interface type='bridge'> <mac address='02:00:c0:a8:31:97'/> <source bridge='vmbr0'/> <virtualport type='openvswitch'> <parameters interfaceid='6e492227-cd8b-f472-9f3d-1161ddf9ecfc'/> </virtualport> <target dev='vnet0'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <input type='mouse' bus='ps2'/> <graphics type='vnc' port='5905' autoport='no' listen='0.0.0.0'> <listen type='address' address='0.0.0.0'/> </graphics> <video> <model type='cirrus' vram='9216' heads='1'/> <alias name='video0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> <memballoon model='virtio'> <alias name='balloon0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </memballoon> </devices> <seclabel type='dynamic' model='apparmor' relabel='yes'> <label>libvirt-cff38c6a-2996-7709-c4f4-0ed826c2fb02</label> <imagelabel>libvirt-cff38c6a-2996-7709-c4f4-0ed826c2fb02</imagelabel> </seclabel> </domain>
On 08/20/13 16:00, Tobias Brunner wrote:
Hi,
I'm trying to create a snapshot from a KVM VM:
# virsh snapshot-create one-5 error: unsupported configuration: internal checkpoints require at least one disk to be selected for snapshot
How can I debug this error message and what does it mean?
An internal snapshot of a VM requires that the VM has at least one disk using a QCOW2 volume or similar. The memory state is saved in that image. Your VM has only a RAW disk image and thus it can't be used for internal snapshot. You can either use an external snapshot (the memory image is stored separately), but the support for external snapshots isn't finished yet (they can't be reverted automatically). The second option is to convert your VM to a qcow2 image file.. Peter
Some system information: * Ubuntu 13.04 64Bit * virsh --version: 1.0.2 * The XML of the VM is below
Thanks for all help...
Cheers, Tobias
<domain type='kvm' id='4'> <name>one-5</name>
...
<disk type='network' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source protocol='rbd' name='one/one-5-5-0'/> <target dev='hda' bus='ide'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk>
Hi, Thanks a lot for the answer.
An internal snapshot of a VM requires that the VM has at least one disk using a QCOW2 volume or similar. The memory state is saved in that image. Your VM has only a RAW disk image and thus it can't be used for internal snapshot.
Ok, that makes sense...
You can either use an external snapshot (the memory image is stored separately), but the support for external snapshots isn't finished yet (they can't be reverted automatically).
How can I create an external snapshot?
The second option is to convert your VM to a qcow2 image file..
...
<disk type='network' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source protocol='rbd' name='one/one-5-5-0'/> <target dev='hda' bus='ide'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk>
As you can see, I'm using RBD as storage backend. So converting to a qcow2 is not an option. Any idea how to achieve internal snapshots using RBD as storage backend? F.e. attach an additional qcow2 disk just for the snapshot? Cheers, Tobias
On 08/20/2013 09:13 AM, Tobias Brunner wrote:
Hi,
Thanks a lot for the answer.
An internal snapshot of a VM requires that the VM has at least one disk using a QCOW2 volume or similar. The memory state is saved in that image. Your VM has only a RAW disk image and thus it can't be used for internal snapshot.
Ok, that makes sense...
You can either use an external snapshot (the memory image is stored separately), but the support for external snapshots isn't finished yet (they can't be reverted automatically).
How can I create an external snapshot?
Add '--disk-only' for an offline domain, or use 'virsh snapshot-create-as --memspec' instead of 'snapshot-create' for an online guest (you can also use snapshot-create for an external snapshot, but you have to write appropriate XML for the case, rather than relying on the no-arg option that provides a default XML for an internal snapshot; so I find snapshot-create-as a lot easier to work with).
The second option is to convert your VM to a qcow2 image file..
...
<disk type='network' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source protocol='rbd' name='one/one-5-5-0'/> <target dev='hda' bus='ide'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' target='0' unit='0'/> </disk>
As you can see, I'm using RBD as storage backend. So converting to a qcow2 is not an option. Any idea how to achieve internal snapshots using RBD as storage backend? F.e. attach an additional qcow2 disk just for the snapshot?
Internal snapshots require qcow2 (or the less-used qed) file format, full stop. If you want your snapshots to live on RBD storage backend, then you either layer the qcow2 file on top of that backend, or you use external snapshots. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
The 21/08/13, Eric Blake wrote:
On 08/20/2013 09:13 AM, Tobias Brunner wrote:
Internal snapshots require qcow2 (or the less-used qed) file format, full stop. If you want your snapshots to live on RBD storage backend, then you either layer the qcow2 file on top of that backend, or you use external snapshots.
And another option would be to use LVM on top of RBD. -- Nicolas Sebrecht
participants (4)
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Eric Blake -
Nicolas Sebrecht -
Peter Krempa -
Tobias Brunner