On Tue, Jun 30, 2009 at 10:19 PM, jakjr <joao.alfredo@gmail.com> wrote:

Why not use a Multi-Master replication for this situation ?

I don't propose one or the other. But here are some thoughts against :

http://www.watersprings.org/pub/id/draft-zeilenga-ldup-harmful-02.txt

The core issue for me seems to be conflicts with determining who has the "newest" data, and efficiency of transfer. If replication is predominantly in one direction, the replication works better with less latency and there is less opportunity for conflicts.

Mirrormode and multimaster are configured the same in openldap, as i understand it, except it is called mirrormode when you primarily write through one node most of the time.

In mirrormode both nodes keep a full copy of the DIT so it has the benefits of full redundancy, but without the possibility where both servers get an update at the same time for the same data, and cannot resolve the conflict themselves (in which case one server will be wrong).

There is also the side benefit / last resort of having two seperate sets of BDB transaction logs, to help recover consistancy in the event of one serious server failure or bdb corruption due to improper power / shutdowns etc.,

Cheers
Brett