The intent of this white paper is to give you a better understanding of the different components of IBM Lotus® Sametime® 7.5.1 and 8.x servers and their environments, so you can better troubleshoot problems that may occur. We address both the stand-alone Sametime (chat or meeting) server as well as the Sametime Enterprise Meeting Server (EMS), which provides clustering, load balancing, and central administration for Sametime meeting servers.

http://download.boulder.ibm.com/ibmdl/pub/software/dw/lotus/STServerT-shootingFinal.pdf