[pve-devel] About PVE Backup Integration Guide

[Fiona Ebner]

Am 18.03.25 um 09:59 schrieb Prashant Patil:
> We have tried the steps mentioned here to create copy-before-write snapshot - https://www.mail-archive.com/qemu-devel@nongnu.org/msg876056.html
> 
> However, one of the commands 'blockdev-replace' fails with below error:
> {"error": {"class": "CommandNotFound", "desc": "The command blockdev-replace has not been found"}}
> 
> Is the command available in any specific qemu version? Is there any other command that we should be using instead if blockdev-replace?

No, it has not yet been implemented neither upstream nor downstream. The
latest proposed iteration is here [0].

> We are happy to integrate with backup provider APIs if they are stable and ready for the integration. On this same thread, I had asked few questions about APIs timelines. Could you please help us to get that info?

Thomas already answered this in the very first response:

> We would be open to fast-track this effort for inclusion with feedback
> from backup vendors. While there are other ways to hook one in, these
> are not nice and can cause problems – so in the long term we expect that
> most/all backup vendors will switch to this plugin method, at least for
> supported setups.

I sent v5 of the patch series today [1]. Again, I would highly recommend
to try and develop your solution with that API for proper integration.
Otherwise, it's 100% up to you not to cause conflicts with the Proxmox
VE system with your backup solution, and naturally, we cannot give you
much help with development (or later with debugging user issues) of a
fully separate backup stack.

It would be appreciated if you could give us feedback and tell us what
parts of it work and what parts might be difficult to work with for your
scenario. Then we might still be able to adapt to your requirements.
Adapting things retroactively means that there is less freedom to change
the interface, so now is the best chance.

[0]:
https://lore.kernel.org/qemu-devel/20240626115350.405778-1-vsementsov@yandex-team.ru/
[1]:
https://lore.proxmox.com/pve-devel/20250321134852.103871-1-f.ebner@proxmox.com/T/

Best Regards,
Fiona