Quaanh,
I did not use -q on slapadd.
Essentially I do a slapadd -f /etc/openldap/slapd.conf -b o=myco,c=us, -v -w > load_myco.log
We have three databases, so there are three slapadd above with -b o=myapps,c=us -v -w > load_apps.log and a -b o=mycust,c=us -v -w > load_cust.log
We have a very large custom schema and three databases, so we are still using slapd.conf instead of cn=config. The schema dates back to the 1990s.
The database is "bdb" on all three schemas.