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Re: Active/Active servers
Buchan Milne wrote:
On Thursday 06 December 2007 13:46:28 Taymour A. El Erian wrote:
I am not sure if this is the right place to ask this or not. If I
install 2 nodes of OpenLDAP and they both share the same SAN storage, is
it possible that both of them would be working active/active ?, i.e.
behind a load balancer (doing reads and writes).
Sharing the same storage is typically what one would do with an Active/Passive
HA cluster, using a cluster middleware to avoid both nodes accessing the
storage simultaneously (and moving the resource IP etc. with it).
The only real way to do active/active for writes is multimaster replication in
2.4. But, do note that all it buys you is a cheaper solution (e.g., no SAN
required), not a faster one.
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.
-- 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/