I suppose maybe I didnt understand what the problem was. I had understood you to not want to transfer backups when no change was present.
You could have started here and make the whole thread unnecessary. You dont actually NEED vzdump at all to...
The issue isnt EXACTLY the baseline virtual cpu model (although this comes to play too) but rather the presence/absence of specific feature flags and/or hw vulnerability mitigations.
The X86-vX models essentially are presets for flags, and...
You're trying to reinvent the wheel.
Moden backup strategies are differential, which means that they are
- content aware (via CBT)
- only transfer the changes
the "simple" vzdump process is not content aware, so you would have to resort to...
1. lxc.
2. "decent" speeds are very relative. your tps on this system will be abysmal in the best of cases, and will drop as soon as you start hammering the system.
3. running the container in unprivileged mode.
4. since all you need is...
your use case is more suited for snapraid or unraid. these dont integrate with pve in any way, but they will work normally like any directory type store.