Previously I was using OpenLDAP 2.1.x and 2.2.x with ldbm backend.
I never had problems with it.
As I've read on the list that ldbm support will be dropped in the next
major version of OpenLDAP, and bdb is the recommended backend, I
decided to deploy a couple of new OpenLDAP servers with bdb backend.
Unfortunately, the choice was a disaster - a couple of tests showed
that after powering off the server, OpenLDAP is not able to start
all I see in logs is a single message (loglevel 256):
bdb_db_open: unclean shutdown detected; attempting recovery.
And that's it, it never recovers.