I'm currently running a fairly simple LDAP environment of two OpenLDAP 2.3 servers with a Master & Slave relationship using syncrepl. These servers are currently being used for authentication and for sendmail routing. I'm hoping to upgrade these two OpenLDAP 2.4 and create some sort of multi-master environment so that I can accept writes when one or more of the servers is down. I'd also like to add 2 more servers to the pool. I have two questions: 1) does anyone have any advice for things to watch out for when updating from 2.3 to 2.4? 2) what should I use for replication? Can I use some combination of MirrorMode and Multi-Master replication? This statement worries me: "Breaks the data consistency guarantees of the directory model" what does it mean? I found that here: http://www.openldap.org/doc/admin24/replication.html is that only a concern when the servers get out of sync as far as time goes? Any advice would be appreciated.