Pool File: unknown

I'm using openldap 2.4.16 with bdb 4.6 backend on one master and one slave with syncrepl in refreshAndPersist mode.

Running 'db_stat -m' on the slave I have 9 entries like that:

Pool File: unknown 1024 Page size 0 Requested pages mapped into the process' address space 133 Requested pages found in the cache (99%) 1 Requested pages not found in the cache 2 Pages created in the cache 0 Pages read into the cache 0 Pages written from the cache to the backing file

I have no such entry on the master.

Can someone please explain?

Regards, Thierry