Buchan Milne wrote: 
On Friday 29 August 2008 17:59:39 Ivan Ordonez wrote:
  
Hi all,

We have a small size domain with about 500 users and computers.  We are
using Samba with Openldap integration to authenticate user login and
file sharing.  Our setup is consist of 3 servers running Gentoo Linux -
1PDC and 2BDCs.  As for replication, we are still using "slurpd".  Any
changes or modification is done through the PDC which replicates the
changes to BDC1, then from BDC1, it then goes down to BDC2 - it's like a
chain.
    

Why? Why not have PDC replicate to BDC1 and BDC2?

You didn't provide your OpenLDAP version (which is quite important in 
discussing the options).
I'm sorry for not providing as much information as I can.  We are using openldap version 2.3.43 and samba 3.0.31.

Having the PDC replicate to BDC1 and BDC2 to me seems a little risky.  What happen if the PDC crashed?  Will you have to configure one of the BDC to be the new PDC?  We want to make it act like a Windows domain type of replication where we can use any of the DCs to make changes.
  
We want to start using "syncrepl" soon as a way to replicate our
database but I'm not sure were to start.  We want to setup all of our
machine to sync with each other everyday,
    

Only once a day?? Syncrepl in RefreshAndPersist will be immediate (as or more 
immediate than slurpd, with fewer problems regarding resyncing etc.).

What I meant to say is to have all the server sync every time a change is made.  RefreshAndPersist seems like the way to go here.
  
and not worry which machine is
use to make changes, modification, etc....  
    

Changes done via what? Samba has referral chasing, so you don't need multi-
master to have a BDC be able to write to OpenLDAP.

Our BDCs are set in a way that they can only see and read the changes made to samba and ldap.  You can not create account or make any changes on our domain using the BDCs.  That is the way it was setup.
  
I'm not sure which syncrepl
function to use to achieve what we want to do.  Is "N-Way Multi Master
replication" the correct choice to do this?
    

It's not a requirement, and it may be excessive complexity if you just want 
replication to work.

  
We are using "BDB" database
on each servers, and would like to achieve this with minimal downtime if
possible.  What is the best way to do this?
    

Configure syncrepl on the provider and the two consumers, assuming you have a 
recent enough OpenLDAP version, and restart ...

Configuration of syncrepl does require at least:
1)syncprov overlay configured on provider
2)limits and access statements on provider to ensure DNs used by consumers can 
get all entries/attributes
3)entryUUID and entryCSN attributes indexed on all servers
4)syncrepl statements in consumer configuration

(so, your restart may be a stop;slapindex;start for the indexes, but your 
database is small)

Thanks for all your help.
Regards,
Buchan