I keep an eye on the Lotus Support feeds - especially for updates to Technote 1206369 dealing with Integrated awareness on Notes 6.5.x results in server outages. There was an update to this yesterday with some information I was not aware of.
First, I really like this quote: "On iSeries this problem will appear as an abnormal termination of the StMux task. You would probably not notice a CPU spike because the CPU has so much processing power available."
Secondly, from speaking with Tech Support in the past, I'm not entirely certain of the validity of this statement: "Verify that the Sametime server is running Fix Pack 1 (FP1) for Sametime 6.5.1 or is running Sametime version 7.0.". There may be some enhancements to slow down the rate of the crashes in comparison with Sametime 6.5.1 without the FP1, but there is not an actual server-side fix shipped in these releases.
Third, "Upgrade the Notes clients to 6.5.4 CCH6, 6.5.5 CCH1 or 7.0.1 Moving to these releases includes a number of enhancements which reduce the Sametime server load that is driven by Notes IM." We're upgrading now to 7.0.1 Clients (already have 21% of clients at 7.0.1!!), so this should help out our situation. I'm also still working with Support on this problem...
Finally, the option that I just enabled this morning was to "Increase the Domino server name lookup cache (for Sametime servers configured with a Domino directory only)" There are some specifics listed in the technote on how to determine if your name cache is properly sized. My peak and max sizes were equal, so I really needed to adjust this. They suggest setting it to 64MB (or 67108864). Mine was around 16.5MB, so this should be helpful.
Now Playing: "Lost Without You" by John Petrucci