Using borg mount to access an archive or even the whole repository is incredibly powerful and a very nice feature.

Unfortunately, this also locks the repository so that no new archives can be created while an archive from the same repository (or even the repository itself) is mounted.

My understanding is that a mounted archive/repository should be read-only anyways, so I do not see a good reason why a simultaneous borg create should not be allowed. I could even live with new archives added after the mount no being visible.

Background: If you run borg create quite often (like every 15 minutes) and your backed-up sources are quite large, the "restore" window between the end of one borg create and the beginning of the next one shrinks or mere minutes. Inspection of archives, non-standard or long-running restores become unfeasible.

Yes, you could store the repository on btrfs or zfs, create a snapshot of the filesystem containing the repository, mount that btrfs/zfs snapshot on /mnt/repository and then run borg mount off of that - but this seems a bit over the top, plus there are those of us who still use ext4 or similar, non-snapshotting file systems.

Changing the code so that borg mount does not lock the repository seems like a huge improvement in usability.