Prime's ruling 2026-10-02. retention.py picks the snapshots to delete:
the newest 48, plus the newest of each of the last 30 days and of each of
the last 12 ISO weeks, counting only days and weeks that have snapshots.
Names that are not exactly YYYY-MM-DD_HHMM are never selected, and the
NAS side refuses any path outside that pattern. The unit fails unless
the number kept equals the number expected. Live run: deleted 1, 0
errors, 48 kept as expected.
rsync -a copies a read-only source dir (0555) as read-only, so the hourly
prune's rm -rf could not unlink inside it. From 2026-07-18 every pruned
snapshot was left as a 22-entry husk while the run still logged OK. The
1,740 husks on nh3-nas were removed (0 errors; 48 full snapshots kept).
The prune now runs chmod -R u+w before rm -rf, logs its error count and
the number of snapshots kept, and exits 3 on a failed prune (exit 1 on a
failed rsync) so the systemd unit shows failed instead of passing.
Adds the rsync --link-dest hourly snapshot job (nh3-dev:~/development ->
nh3-nas, 48-snapshot retention, secrets/build-dirs excluded) that closes the
no-off-box-backup gap exposed by the 2026-07-12 working-dir clobber. Script
mirrors the live ~/.config/dev-backup/dev-backup.sh; runbook covers restore.
vh