[sheepdog] Live snapshot not working via libvirt. Possible regression?

[Hitoshi Mitake]

Hi Jason,
Cc: Vasiliy

On Fri, Sep 11, 2015 at 12:20 AM, Jason Noble <noblej at yahoo.com> wrote:
> My understanding from the page at
> https://github.com/sheepdog/sheepdog/wiki/Which-Format-of-QEMU-Images-Should-I-Run
> is that sheepdog can store qemu checkpoints internally using the 'raw'
> format. I am having problems when trying to take a live snapshot of a VM
> stored on sheepdog though. I get the following error message when using
> `virsh snapshot-create --live domain`:
>
> "internal snapshot for disk vda unsupported for storage type raw"
>
> This behavior appears to have been introduced with the following commit:
>
> commit f7c1410b0ee5b878e81f2eddf86c609947a9b27c
> Author: Shanzhi Yu <shyu at redhat.com>
> Date:   Sat Feb 28 17:51:36 2015 +0800
>
>     qemu: snapshot: Don't skip check for qcow2 format with network disks
>
>     When the domain's source disk type is network, if source protocol is rbd
>     or sheepdog, the 'if().. break' will end the current case, which lead to
>     miss check the driver type is raw or qcow2. Libvirt will allow to create
>     internal snapshot for a running domain with raw format disk which based
>     on rbd storage.
>
>     While both protocols support internal snapshots of the disk qemu is not
>     able to use it as it requires some place to store the memory image. The
>     check if the disk is backed by a qcow2 image needs to be executed
>     always.
>
> I reverted the above commit, built libvirt and tried again and got the
> following error:
>
> "error: Operation not supported: live snapshot creation is supported only
> with external checkpoints"
>
> Before digging any further into this issue, I wanted to ask on the mailing
> list if this behavior seems incorrect to others. If this behavior _is_
> expected then I think the wiki page linked in the opening of this email
> should be updated to reflect that.

Thanks for your report. However, I'm not sure about this is a problem
or not because I'm not using libvirt :(

Vasiliy, how do you think about it?

Thanks,
Hitoshi

>
> The versions of qemu, libvirt and sheepdog I'm using are listed below.
>
> jason at sheepdog1:~/sheepdog$ qemu-system-x86_64 --version
> QEMU emulator version 2.3.0 (Debian 2.3+dfsg-0ubuntu1), Copyright (c)
> 2003-2008 Fabrice Bellard
>
> jason at sheepdog1:~/sheepdog$ libvirtd --version
> libvirtd (libvirt) 1.2.16
>
> jason at sheepdog1:~/sheepdog$ sheep -v
> Sheepdog daemon version 0.9.0_165_g01fe35e
>
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