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RE: Active/Active servers

>-----Original Message-----
>From: openldap-software-bounces+jeff_clowser=fanniemae.com@openldap.org
rg] On Behalf Of John Madden
>Sent: Thursday, December 06, 2007 1:39 PM
>To: Howard Chu
>Cc: Buchan Milne; openldap-software@openldap.org; Taymour A. El Erian
>Subject: Re: Active/Active servers
>> Indeed. I wonder why people even think that "load balancing" with
>> storage ever makes sense. The biggest bottleneck in server
performance is disk 
>> throughput. Putting a bunch of fast CPU frontends in front of the
same Bunch 
>> Of Disks isn't going to do squat for write rates, and write rates are
the only 
>> important metric in a replication scenario.>
>I think perhaps the OP is asking the wrong question, sure, but I see a
>great need for the ability to provide a "load balanced" read cluster
>for the performance gains (and there certainly could be some on reads)
>but for the HA.  I'd certainly like to be able to quiesce a node for
>maintenance, take it out of the cluster, patch it, bring it back up and
>have it re-sync, then bring it back into the cluster without any
>interruption in service to the users.  It looks like mirror mode in an
>active/active cluster (behind a load balancer) would allow me to do

Only change to this comment I would make is:  rather than an
active/active master cluster, I'd have it active/hot standby (i.e. the
VIP on the load balancer only directs connections to one master, and
fails over to the other master if that one is unavailable rather than
balancing connections between the two masters all the time, to
avoid/minimize write conflicts).

 - Jeff