Vertical Scaling advantages?

[Former Member]

On a dual CPU host with sufficient memory, is there any advantage to be gained by installing multiple application servers on a single host? Does it make any difference if the host is part of a cluster too? I'm looking at this primarily from an EP perspective, for both WAS 6.20 and WAS 6.40.

The scaling documentation doesn't really give any hard information on this apart from it's possible.

[Former Member · Accepted solution]

Richard,

On our EP6 WAS6.20/40 installations we usually install 2 J2EE engines so that we can stop and restart one of the engines to pick up admin changes e.g. UME settings or to fix and problems or detect new image files in the file system while users are still being serviced by the other.

You also tend to find on boxes with multiple CPUs that the resources arent always utilised fully with a single J2EE engine instance and that you get better overall throughput by having 2 or more engines running. Any kind of scaling is a bit of a black art so its probably best to load test a single instance and monitor the resource usage and ramp up the load until the box seems to be running flat out, and then compare it with two J2EE engine instances running to compare throughput.

Cheers,

Steve