> Just wonder whether weblogic cluster can be configured to not use IP
multicast
> if the clustered servers are running on the same multi cpu box as I would

have
> thought that in memory communication would be a faster option in this

case.

Multicast with a TTL of zero is basically implemented by the OS as a shared
memory approach, so there is usually very little difference in performance.

> This is again as we were told that Weblogic doesnt scale well for more

than 2
> cpus per box.
> If we are using a 4-6 cpu box then in this case it makes more sense to

have 2/3
> instances
> per server communicating via mem and not multicast


The scalability on various numbers of CPUs differs greatly. It is vastly
improved on more recent versions of WebLogic with more recent versions of
the JVM. Back on JVM 1.2 with WL 5.x and earlier, you would have to run
multiple instances in order to "soak" a box. The best way to determine if
this is still the case is to use a load test that (with everything else
equal) will soak the box with multiple JVMs but not with a single one.

Peace,

Cameron Purdy
Tangosol, Inc.
http://www.tangosol.com/coherence.jsp
Tangosol Coherence: Clustered Replicated Cache for Weblogic


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