Re: Fail to write in slave during replication

           updatedn="uid=repl_writer,dc=mycompany,dc=com"

I don't think this is valid. Try "slaptest -d config" and/or read slapd.conf(5) man page.

*The userpassword does not replicate to slave. *The following is the replicated result in slave.

If you modify one of the other attributes (cn/sn/etc.), does it make it from the master to the slave?

Turn up debugging and see what's going on. I'd look for ACL issues first. Are those really your only two access rules?

ldapmodify: Referral (10) referrals:

ldap://master:389/uid=testuser,dc=mycompany,dc=comldap://master:389/uid=repl_reader,dc=ufreight,dc=com

This isn't a problem -- the slave is telling you it's a slave and you should be talking to the master. So that's a sign that your config is on the right track.