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Re: Clustering / failover

James Bourne wrote:
 On Fri, 24 Jun 2005, Quanah Gibson-Mount wrote:
> --On Friday, June 24, 2005 4:16 PM -0600 Michael Martinez
> <mikem@nmt.edu> wrote:
>> So most if not all sites running openldap, only use one master
>> server?

 Not all.

 We use pulse/nanny to monitor the state of the primary master, and
 promote a secondary master to primary and migrate the write server IP
 in the event of failures.

 This comes in really handy if you need to do updates that require
 restarting services or servers and for making it through hardware
 issues.  A single server can handle the load easily but not if it's
 offline.  As well the two write servers can be attached to the
 network via seperate switches both with multiple uplinks to your core
 routers for even more redundancy.

Agreed. But the secondary master is generally just acting as a "hot standby" - it doesn't do anything (besides receive updates from the primary master, just like any other slave) unless the primary master goes down, at which point it can immediately take over as the primary master. This is about the only good use for the "Multimaster" code that currently exists in OpenLDAP.

 -- Howard Chu
 Chief Architect, Symas Corp.       Director, Highland Sun
 http://www.symas.com               http://highlandsun.com/hyc
 Symas: Premier OpenSource Development and Support