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Message Posted: Mon, 24 Apr 2006 @ 21:40:39 GMT

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The SESSION issue is probably due to exceeding some client configuration setting (e.g. ulimit). If your old system had 8 nodes with 7 AMPs per node, for example, the default/max would have been 56 (less than the 64 you indicate is your upper limit now). Your 10 new nodes almost certainly were defined with more than 6 AMPs per node, so the default would have exceeded 64 at that point. But more sessions can only help in Acquisition phase, not Application phase.

The run-time degradation you are seeing is most likely due to skewing (assuming it's the Application Phase that's taking longer). The more AMPs you have, the more pronounced the impact of skew. I'm guessing that your system has plenty of other work running concurrently; otherwise the effects would be partially masked by the "average" AMPs finishing sooner, at which point the "hot" AMPs would be able to consume more than their fair share of resources.

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