# N-Way Multi-Master Replication - OpenLDAP



## hainguyen1402 (May 30, 2011)

Hi all,

Can anybody help me how to configure N-Way Multi-Master Replication? I have read the guide at http://www.openldap.org/doc/admin24/replication.html at session 18.3.3. However, it is not very clear, because I am a newbie of LDAP, so if possible, please help me step by step how to configure it.

Thank you all.


----------



## francis (Jun 2, 2011)

Hi, You know, I wondered whether to write this post, because you asked for explanation, step by step the replication issues. Personally I think that the official handbook is the best source of information. Of course, I realize that it can be also confusing. I'll try to give you some interesting links that, I hope, will help you with the implementation of replication.

The OpenLDAP *N-WAY Multi-Master* mode uses *syncrepl* to replicate data to multiple provider. Supports various topologies. The results (and structure) can be very complicated, but of course, You can have more problems than benefits. It also looks like that every client, in some way, is a provider for the others servers. I mean members of these servers. Each server must have assigned a unique id. I think that in whole process the most important thing will be the slapd.conf file. So let's look;


General Overview of Multimaster Replication This document consists overview of multimaster replication.
RFC 3384 defines multi-master replication Very useful link. Especiall *3. Multi-master Changes to LDAP Service Model*
OpenLDAP MultiMaster Replication Current and working slapd.conf file *syncrepl* settings (source: Michael Martin blog).
zytrax.com/books: Replication & Referral Chapter 7 which provides information about configuring replications for LDAP. Note that there is several interesting contents e.g. *7.2.1.2.3 OpenLDAP syncrepl Multi-Master* etc.
zytrax.com/books: slapd-config file Things about slapd-config file and new feature configuration using a entry called *cn=config*.
novell SUSE Linux OpenLDAP 2.4.x Replication It is a HOWTO which should help you to understand, configure and test replication process. Exhaustive text with several example images. You'll also find arguments for and against Multi-Master replication.
Multi-Master Replication Sample config.
Configuring Multi-Master Replication Good description of whole process.

I think you should also pay attention to the version of OpenLDAP. This seems important because of changes in subsequent editions OpenLDAP Release changes. From what I know, OpenLDAP 2.4 has support for multi-master replication using *syncrepl*.


----------



## hainguyen1402 (Jun 3, 2011)

Thank Francis so much, your reply is very helpful to me. I will try it.


----------

