One spinning disk crashed on Sept. 26th. It was used for Arthur's HOME and backups.
The system is still up, so it is not too urgent. First step is to recover the backup system. The rsync backups are in an inconsistent state, fortunately we have a BORG_BORG backup (a backup of the backup):
epysode:/export/backup$ borg extract --progress borg-borg::BORG_BORG_TUX01-Saturday-20210925-07:12:04
We are adding a new 4TB SSD.