The file should be named /etc/ldap/slapd.d/cn=config/olcDatabase={1}hdb.ldif.
I recommend using loglevel config to see debugging information related to configuration issues. If your file is not read, the hdb database won't appear in the output...
[snip] <= root access granted => access_allowed: search access granted by manage(=mwrscxd) <= test_filter 6 : config_add_internal: DN="olcDatabase={1}bdb,cn=config" no structural objectClass (unrecognized objectClass 'olcBdbConfig') config error processing olcDatabase={1}bdb,cn=config: send_ldap_result: conn=-1 op=0 p=0 [/snip]This part "Unrecognized objectClass 'olcBdbConfig'" surprised me a bit, as the line caused the problem is taken from openldap manual:
5.2.6. BDB and HDB Database Directives
In addition to the olcDatabaseConfig objectClass, BDB and HDB database entries must have the olcBdbConfig and olcHdbConfig objectClass, respectively.
One would usually add the new configuration object via LDAP, rather than by modifying the database files. This is the point of cn=config. However, adding files may work also...