OpenLDAP: unknown directive <syncprov-checkpoint> inside backend database definition

Question

Trying to setup the "mirror mode" of 2 OpenLDAP instances on 2 separate servers. But slapd failed to start due to the new added directives. Below is error msg in /var/log/ldap.log:

  /etc/openldap/slapd.conf: line 127: unknown directive <syncprov-checkpoint> inside backend database definition.

Below is the ENV:

# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.3 (Maipo)
# rpm -qa | grep openldap
openldap-devel-2.4.40-13.el7.x86_64
openldap-2.4.40-13.el7.x86_64
openldap-servers-2.4.40-13.el7.x86_64
openldap-clients-2.4.40-13.el7.x86_64
# ps -ef | grep slapd
root       2224      1  0 Feb17 ?        00:00:10 slapd

Below are the sync part in /etc/openldap/slapd.conf file on the server:

# Load dynamic backend modules:
# Module syncprov.la is now statically linked with slapd and there
# is no need to load it here
modulepath /usr/lib64/openldap

...

# enable monitoring
#database monitor

# allow onlu rootdn to read the monitor
#access to *
#        by dn.exact="cn=Administrator,dc=example,dc=com" read
#        by * none
syncprov-checkpoint 100 10
syncprov-sessionlog 100

serverID    1

syncrepl      rid=001
              provider=ldap://10.1.10.19
              bindmethod=simple
              binddn="cn=Administrator,dc=example,dc=com"
              credentials=ldap
              searchbase="dc=example,dc=com"
              schemachecking=on
              type=refreshAndPersist
              retry="60 +"

mirrormode on

loglevel -1

Answer 1

This issue is resolved today by myself. It turns out that the comment on "syncprov.la" is "accidentally" wrongly added. Don't know who and why.

After re-reading the manual and add the "moduleload syncprov.la" on both servers, it is resolved.

It is no wonder no one ever post same question.