You get the following error attempting to start the ldap service.

service ldap start

You can get this error when instances of LDAP are already running, this can occur if LDAP has not properly shutdown in a LDAP stop event or other condition when the database is already locked. You may also have other LDAP-type processes listed.

[root@server ~]# ps afxw | grep ldap
3487 ? S 0:00 ldapsync
3501 ? S 0:00 \_ ldapsync
18278 ? Ss 0:00 /usr/sbin/saslauthd -m /var/run/saslauthd -a ldap
18284 ? S 0:00 \_ /usr/sbin/saslauthd -m /var/run/saslauthd -a ldap
18285 ? S 0:00 \_ /usr/sbin/saslauthd -m /var/run/saslauthd -a ldap
18286 ? S 0:00 \_ /usr/sbin/saslauthd -m /var/run/saslauthd -a ldap
18287 ? S 0:00 \_ /usr/sbin/saslauthd -m /var/run/saslauthd -a ldap
1445 pts/0 S+ 0:00 \_ grep ldap
31871 ? S 0:00 sh -c /usr/bin/sudo /usr/sbin/slapcat -n3 -l /etc/openldap/backup.ldif 2>&1
31872 ? S 0:00 \_ /usr/sbin/slapcat -n3 -l /etc/openldap/backup.ldif

To solve this issue, stop all instance of LDAP.

service ldap stop
ps aux | grep ldap

If LDAP does not stop you may be required to stop the individual processes using the kill command. We recommend that you use these kill commands in the following order:

kill -15 [pid]
ps aux | grep ldap

If that doesn't work:

kill [pid]
ps aux | grep ldap

If that doesn't work:

kill -9 [pid]
ps aux | grep ldap