slapd failed to start. Why did ownership of the ldap transaction log (log.0000000001) change to the root user?

Issue

• Slapd failed to start with the following messages, how to recover? What is the reason?

  # service ldap start
  Checking configuration files for slapd:  bdb_db_open: unclean shutdown detected; attempting recovery.
  bdb_db_open: Recovery skipped in read-only mode. Run manual recovery if errors are encountered.
  bdb(dc=XXXXXX,dc=jp): PANIC: fatal region error detected; run recovery
  bdb_db_open: Database cannot be opened, err -30974. Restore from backup!
  bdb(dc=XXXXXX,dc=jp): DB_ENV->lock_id_free interface requires an environment configured for the locking subsystem
  backend_startup_one: bi_db_open failed! (-30974)
  slap_startup failed (test would succeed using the -u switch)
  

• db_hotbackup stops with the following error:

  db_hotbackup: BDB0060 PANIC: fatal region error detected; run recovery
  db_hotbackup: DB_ENV->log_archive: BDB0087 DB_RUNRECOVERY: Fatal error, run database recovery
  db_hotbackup: BDB1581 File handles still open at environment close
  db_hotbackup: BDB1582 Open file handle: /var/lib/ldap/__db.001
  db_hotbackup: BDB1582 Open file handle: /var/lib/ldap/__db.002
  db_hotbackup: BDB1582 Open file handle: /var/lib/ldap/__db.003
  db_hotbackup: BDB1582 Open file handle: /var/lib/ldap/./log.0000000130
  db_hotbackup: BDB0060 PANIC: fatal region error detected; run recovery
  db_hotbackup: dbenv->close: BDB0087 DB_RUNRECOVERY: Fatal error, run database recovery
  db_hotbackup: BDB5043 HOT BACKUP FAILED!