[pve-devel] [PATCH-SERIES v8 pve-storage/qemu-server] add external qcow2 snapshot support

[Fabian Grünbichler]

> Thomas Lamprecht <t.lamprecht at proxmox.com> hat am 14.07.2025 13:11 CEST geschrieben:
> 
>  
> Am 14.07.25 um 13:04 schrieb Fabian Grünbichler:
> >> so I think that a warning in the UI is fine enough if qcow2 format is
> >> selected.
> > would probably need to go into a few places then (allocating a disk,
> > moving it, restore of backup - at least?)
> 
> 
> We might be able to add it relatively centrally to the storage selector,
> or a new wrapper component, and then enable an option (or switch to the
> new wrapper component) - Dominik probably would have a good idea where
> this could fit nicely.
> 
> Albeit, taking a step back, I'm not so sure if that really helps the user?
> I.e., what's something actionable they can do when seeing such a warning?
> Is it just to signal "this is a tech preview, be wary"? If, then I'd rather
> just signal that in the storage edit/add window.

for LVM, there is no new plugin or storage option, the plugin just gains
a new supported format and that has the experimental status. we could
guard that (like in the DirPlugin) with the external-snapshots flag, and
only allow qcow2 formatted volumes if that is set - that way, users would
need to "opt-in" to the experimental behaviour by creating a new storage
with that flag set. if we don't do that, then the only thing that we can
warn about is qcow2 *being used*, and there is no central place for that
as all existing LVM storages would get that support "over night" (once
they upgrade).