libvirt users - Aug 2013 - Re: 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