[pve-devel] Proposal: support for atomic snapshot of all VM disks at once

[Ivaylo Markov]

Hi,

On 07/10/2024 09:12, Fabian Grünbichler wrote:
>> Dietmar Maurer <dietmar at proxmox.com> hat am 04.10.2024 17:13 CEST geschrieben:
>>> I am the maintainer of StorPool’s external storage plugin for PVE[0]
>>> which integrates our storage solution as a backend for VM disks. Our
>>> software has the ability to create atomic (crash-consistent) snapshots
>>> of a group of storage volumes.
>> We already make sure that shaphots of a group of volumes are atomic at qemu level (VM is halted while snapshots are created), so I wonder
>> if there is any real advantage here?
> I think the main advantage is that if you are fine with crash-equivalent consistency (e.g., the same as pulling the power plug) for your snapshots, then you can skip the freeze/suspend (and associated, hopefully tiny, downtime), and just snapshot on the storage layer. there might also be additional optimizations or administrative benefits on the storage side (like all snapshots being part of a single transaction), but those are probably not relevant for PVE itself..
>
This is exactly it - we're looking to avoid any slow downs/interruptions 
in the VMs when creating snapshots. I've not measured how long other 
storage plugins take to create snapshots, but it could be helpful for 
them if it's a slow operation.

-- 
Ivaylo Markov
Quality & Automation Engineer
StorPool Storage
https://www.storpool.com