document LDAP backups

howto/ldap.md

@@ -865,6 +865,12 @@ label.
 <!-- where are the logs? how long are they kept? any PII? -->
 <!-- what about performance metrics? same questions -->
 
+## Backups
+
+There's no special backup procedures for the LDAP server, it is
+assumed that the on-disk `slapd` database can be backed up reliably by
+Bacula.
+
 ## Other documentation
 
  * [userdir-ldap source code](https://salsa.debian.org/dsa-team/mirror/userdir-ldap)