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/ >
