How to keep backups if I am away from the PC for a very long time

[Zesko]

My backup strategy:

• The btrbk systemd timer automatically creates one backup per day on my different disk.
• I want to keep 30 backups (snapshots) on this disk. (30 backups / 30 days)
• If backups are more than at least 30 number, the oldest backups should be deleted automatically until exactly 30 backups are kept.

My config:

timestamp_format        long

snapshot_preserve_min   latest 
snapshot_preserve       no

volume /btrfs
  snapshot_dir  /btrfs/@snapshots/btrbk_snapshots
  target_preserve_min    30d
  target_preserve        no
  subvolume @home
     target send-receive /backup/btrbk_backup/home
  ...

The issue:

If my PC is offline for 2 months long, but all snapshots are older than 30 days and are deleted automatically when my PC is on. They would be gone. No backup.

Have you any idea how to keep 30 backups (snapshots) regardless of age?

[Zesko]

It relates to the issue https://github.com/digint/btrbk/issues/388