[pbs-devel] [RFC proxmox-backup 3/4] datastore: move snapshots to trash folder on destroy

[Christian Ebner]

On 4/22/25 09:54, Fabian Grünbichler wrote:
> 
> renaming the snapdir or moving it to an explicit (per-group?) trash dir are
> the same solution with all the same upsides and downsides, AFAICT. you still
> need to carefully reason about both directions (moving to trash and undoing),
> in particular about interactions with GC. you still have the issue of multiple
> cycles of moving to trash, adding the snapshot again, moving to trash again
> (which can be handled, but is more involved compared to the flag approach),
> when to lock both the trashed and the regular snapdir (or whether there is
> a single lock covering both?), etc.pp.
> 
> I don't think there is any strict technical blocker for either approach, and
> both have pros and cons that need to be weighed. I don't see a clear winner
> (yet), maybe others have a strong(er) opinion?

Since it is also required to keep the backup groups and namespaces 
around when pruning these, the suggested approach with using a marker 
file for trashed snapshots seems best. This allows to apply the same 
marker approach to these as well.

Re-creation of the same group would however require to clear all the 
trash content for these backup groups in order to not run into 
ownership/consistency issues.