I've seen the documentation that describes adjusting the number of threads based on you latency and number of users. I suspect that there is a limit to the latency between the Exchange 2010 and UC server or is there? If you use the formula for the number of threads as shown below and keep increasing the latency until you reach the 64 thread limit it looks like you could have latency as large as 241 ms and 10,000 single inbox users and even a higher latency with few users (497 ms for 5000). At some point the user experience becomes an issue but is there are point where the EWS protocol used to do the sync between the UC and Exchange fails? A related question is what if the UC server is talking to more than one Exchange server or CAS Array?
(Number of Connection single-inbox users * (latency in milliseconds + 15) ) / 40,000 = Number of connections
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.