I have issue where most of the LDAP entries in slave are getting deleted whenever master is getting updated.

First, I am populating all the entries from master.ldif file then starting synchronization. All the entries in master and slaves are same till master is getting updates. Once master is updates and slave requests for synchronization at that time entries are getting deleted.

How to overcome this issue?

I am using following set-up in slave:
syncrepl rid=1
provider=ldap://server
binddn="cn=manager,dc=example,dc=com"
bindmethod=simple
credentials=secret
searchbase="dc=example,dc=com"
interval=00:01:00:00
type=refreshOnly
scope=sub
schemachecking=off
overlay syncprov

What are the setting to see logs in details as Master and slave's log file is not giving any information about this error. I am using syslog.conf with local4* /var/log/ldap.log to populate ldap logs in CentOS.