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Random Exchange client hang-up fix

What to do when clients seem to be disconnected.


Random Exchange client hang-up fix
Serdar Yegulalp

Users of Exchange Server have reported that sometimes Exchange clients will become unresponsive for minutes at a time. If this happens, chances are the RPC (Remote Procedure Call) service on your Exchange server may be overloaded. Since RPC deals with messages in a synchronous queue, slow clients may cause the RPC server to "hang" temporarily.

To get around this, increase the following registry entries to change the number of threads devoted to Exchange message processing.

HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMSExchangeISParametersSystemMax Threads(Public+Private)

HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMSExchangeISParametersSystemMinimum Threads

According to Microsoft, a maximum of 200 on a quad-processor system (and a minimum of 100) worked excellently. That works out to about 50 threads per processor, although with processors faster than 1.5 GHz you can probably get away with up to 100. Note also that jacking up the thread count too much will hang the server, so keep an eye out when you change these settings.

On a machine with more than 800 MB of RAM, make sure you have the latest Exchange Server service pack if you're using Exchange 5.5, or the machine will hang when it tries to allocate memory improperly.

Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter.

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