Re: [pve-devel] [PATCH qemu-server v2 3/6] migration: fail when aliased volume is detected

[Aaron Lauterer <a.lauterer@proxmox.com>]

On 5/22/23 16:17, Fiona Ebner wrote:
> Am 12.05.23 um 14:40 schrieb Aaron Lauterer:
>> Aliased volumes (referencing the same disk image multiple times) can
>> lead to unexpected behavior in a migration.
> 
> Not only migration, but snapshots, storage locking, etc. Should we
> actually care here? I still think it is rather something that people
> should be made aware for the storage layer. Maybe a big enough warning
> in the documentation is enough?
> 
> Since it's not only migration, should we add a warning during VM startup
> instead/additionally?
> 

I guess a warning in the docs would be a low-hanging fruit -> added to my TODO.
Snapshots should just fail the second time as we already have one with the same 
name, right?

AFAIU storage migration is a case where an aliased volume can lead to very 
unexpected behavior, like storages running full. So a check and die is probably 
a good idea.

An additional warning during startup could probably be a good idea. In that 
case, the checks should probably be factored out into their own method so we can 
call it from the start as well. Though that would probably mean, another round 
of iterating through the config instead of inlining it.