Re: Multi Master Enviornment for Openldap 2.3

[Alex Samad <alex@samad.com.au>]

On Fri, Feb 02, 2007 at 02:52:21AM -0800, Howard Chu wrote:
> Alex Samad wrote:
> >On Thu, Feb 01, 2007 at 10:57:46PM -0800, Howard Chu wrote:
> >>Zhang William wrote:
> >>
> >>>chain + sync cant handle any request if master is down.
> >>>
> >>>I made some modifications before so that a client will change into 
> >>>master and other clients will connect to it in case master is down, 
> >>>but it is only academic.
> >>>
> >>>the architecture "HA + LB cluster" has been rised  long before, but it 
> >>>seems openldap team doesnt implement it gracefully yet :-(
> >>As noted in many previous messages, mirrormode addresses this situation 
> >>automatically.
> >But with one exception you can't write to both database at the same time
> 
> Right, nor do you need such a capability for a high-availability solution.
Sorry I am lost, if I set up 2 nodes (as a side question can you have more than
2 nodes in mirrormode ?) in mirror mode. server A and server b.

and then setup dns round robin to balance the load, or should I use a load
balancer in front of them.  But how do I guarantee that I don't write to both
at the same time.  The only way I can think of do that is to point all the
clients to server A and then fail back to server b.

When I think of a multi master solution, I think of something like oracle rac's
solution or novell's NDS (form memory it is a ldap tree, configured in multi
master mode, I might be wrong).  with Oracle rac you can write to any of the
nodes and it handles it properly (albeit the oracle rac setup uses shared
storage)



> 
> -- 
>   -- Howard Chu
>   Chief Architect, Symas Corp.  http://www.symas.com
>   Director, Highland Sun        http://highlandsun.com/hyc
>   Chief Architect, OpenLDAP     http://www.openldap.org/project/
>