KVM Snapshot with Ceph

[Vincent Hermes <vi...@gmail.com>]

Hi Guys,

so we have built a Cluster with a few CentOS7 CS Nodes with KVM as the Hypervisor AND Ceph as Primary Storage in a hyperconverged way and we got something interesting, maybe some of you have an idea whats up with that. As KVM works with QCOW2 Image Format for its VMs, all of the Storage Volumes and Templates are QCOW2 Files. However trying to take a Snapshot including RAM ends with the error "We only support create vm snapshots from vm with QCOW2 image". Trying a "virsh snapshot-create [vm-id]" brings us "error: unsupported configuration: internal snapshot for disk vda unsupported for storage type raw". The qemu.log states "-drive [...] format=raw [...]" and the according XML file of the VM of course says the same.

Do you have experience in getting Snapshots to work with KVM and Ceph in CS?

Many thanks in advance and best regards from Germany

Vincent

Re: KVM Snapshot with Ceph

[Vincent Hermes <vi...@gmail.com>]

Hi Simon,

ok thank you that's quite a simple explanation.

Greetings
Vincent

On 2020/06/10 16:49:20, Simon Weller <sw...@ena.com.INVALID> wrote: 
> Vincent,
> 
> VM Snapshots aren't supported with Ceph as the primary storage. As you note, when using QCOW2 files, the memory payload for the VM snapshot is included within the QCOW2 file. Since Ceph is using raw storage, there is no where to store that memory (at least today).
> Storage based snapshots are supported on Ceph though and you can snap any disk instance using the native Ceph snapshot functionality.
> 
> -Si
> 
> 
> ________________________________
> From: Vincent Hermes <vi...@gmail.com>
> Sent: Wednesday, June 10, 2020 9:51 AM
> To: users@cloudstack.apache.org <us...@cloudstack.apache.org>
> Subject: KVM Snapshot with Ceph
> 
> Hi Guys,
> 
> so we have built a Cluster with a few CentOS7 CS Nodes with KVM as the Hypervisor AND Ceph as Primary Storage in a hyperconverged way and we got something interesting, maybe some of you have an idea whats up with that. As KVM works with QCOW2 Image Format for its VMs, all of the Storage Volumes and Templates are QCOW2 Files. However trying to take a Snapshot including RAM ends with the error "We only support create vm snapshots from vm with QCOW2 image". Trying a "virsh snapshot-create [vm-id]" brings us "error: unsupported configuration: internal snapshot for disk vda unsupported for storage type raw". The qemu.log states "-drive [...] format=raw [...]" and the according XML file of the VM of course says the same.
> 
> Do you have experience in getting Snapshots to work with KVM and Ceph in CS?
> 
> Many thanks in advance and best regards from Germany
> 
> Vincent
> 

Re: KVM Snapshot with Ceph

[Simon Weller <sw...@ena.com.INVALID>]

Vincent,

VM Snapshots aren't supported with Ceph as the primary storage. As you note, when using QCOW2 files, the memory payload for the VM snapshot is included within the QCOW2 file. Since Ceph is using raw storage, there is no where to store that memory (at least today).
Storage based snapshots are supported on Ceph though and you can snap any disk instance using the native Ceph snapshot functionality.

-Si


________________________________
From: Vincent Hermes <vi...@gmail.com>
Sent: Wednesday, June 10, 2020 9:51 AM
To: users@cloudstack.apache.org <us...@cloudstack.apache.org>
Subject: KVM Snapshot with Ceph

Hi Guys,

so we have built a Cluster with a few CentOS7 CS Nodes with KVM as the Hypervisor AND Ceph as Primary Storage in a hyperconverged way and we got something interesting, maybe some of you have an idea whats up with that. As KVM works with QCOW2 Image Format for its VMs, all of the Storage Volumes and Templates are QCOW2 Files. However trying to take a Snapshot including RAM ends with the error "We only support create vm snapshots from vm with QCOW2 image". Trying a "virsh snapshot-create [vm-id]" brings us "error: unsupported configuration: internal snapshot for disk vda unsupported for storage type raw". The qemu.log states "-drive [...] format=raw [...]" and the according XML file of the VM of course says the same.

Do you have experience in getting Snapshots to work with KVM and Ceph in CS?

Many thanks in advance and best regards from Germany

Vincent