Quanah Gibson-Mount wrote:

--On Friday, July 06, 2012 1:41 PM +0200 Pieter Baele pieter.baele@gmail.com wrote:

...

I've 2 servers in MirrorMode, a part of the tree wil also be partially replicated to 3 slaves.

Do I really need an LDAP proxy or Load balancer(s) so writes are only directed to one server? In our LDAP, the number of writes will be very very low, most of them will be reads (authentication, ssh keys, puppet nodes...)

Any benefit in using 'normal' n multimaster instead of MirrorMode?

You don't have to redirect writes to just one server and set up heartbeat monitoring etc? Mirrormode is just N-way multimaster with a proxy/balancer in front of it. Whether or not that is what you want is up to you to decide. ;)

Personally, I'm just using delta-syncrepl based N-Way MMR.

The virtue of using MirrorMode is that you know for certain that you will never have an unresolvable data inconsistency due to conflicting writes being applied at two different masters at once.

Aside from that, yes, it's just N-Way multimaster.

On 10/07/12 15:11 +0200, Pieter Baele wrote:

On Sat, Jul 7, 2012 at 12:33 AM, Howard Chu hyc@symas.com wrote:

The virtue of using MirrorMode is that you know for certain that you will never have an unresolvable data inconsistency due to conflicting writes being applied at two different masters at once.

Perfect. I don't want inconsistent data :-)

Any recommendation for the frontend? HAProxy, dedicated Load balancers, Pound or OpenLDAP Proxy?

The discussion on this topic has been quiet.

I am looking at using a pair of Linux virtual servers (LVS) using keepalived, having only one machine in the VIP (virtual IP), and the other master being a "sorry server", so that there is one machine that is preferred.

We write to our LDAP masters using some middleware we have written, and I am looking at either making the VIP one for the middleware, or making it a VIP for LDAP, with the middleware writing to the VIP, and possibly having slaves slaving off the VIP, so the health checkers are either checking the LDAP or checking the middleware.

At the moment, I am leaning towards making the middleware the VIP, and having the slaves slave from both masters; though I need to do some more experiments.

I would be glad to hear of the results of your work.