-----Original Message----- From: openldap-software-bounces+jeff_clowser=fanniemae.com@openldap.org
[mailto:openldap-software->bounces+jeff_clowser=fanniemae.com@openldap.o 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
shared
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
not
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 that.
John
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