Continued work on backup script, methodology

docs/backup_restore.md

@@ -33,6 +33,25 @@ Example with Synology mount:
 SYNOLOGY_BACKUP_DIR=/mnt/synology/transcription-backups sh deploy/backup/create_postgres_backup.sh
 ```
 
+## 2.1 Persisting Synology mount (LXC)
+
+The backup copy step depends on a mounted NAS path. Manual `mount` commands are lost after reboot unless persisted.
+
+Use the template (copy, edit placeholders, then run):
+
+```bash
+cp deploy/backup/mount_synology_cifs.example.sh /root/mount_synology_cifs.sh
+nano /root/mount_synology_cifs.sh
+sh /root/mount_synology_cifs.sh
+```
+
+Then add the printed `/etc/fstab` line (with your real values) so the mount survives reboot.
+
+Recommended pattern:
+
+- Keep NAS credentials in a local file like `/etc/samba/credentials/transcription-synology` with `chmod 600`.
+- Keep `SYNOLOGY_BACKUP_DIR` in `.env.production` aligned to that mount point (for example `/mnt/synology-backups`).
+
 ## 3. Restoring from backup
 
 Restore requires downtime for app + worker writes.