How to speed up a large Exchange 2010 Migration
Throttling the Mailbox Replication Service
If you go to your CAS server and navigate to the c:\Program Files\Microsoft\Exchange Server\V14\Bin\MSExchangeMailboxReplication.exe.config file using a text editor such as Notepad, you will see the following settings at the bottom of the config file.By default, the CAS servers are set to: MaxActiveMovesPerSourceMDB = “5″ MaxActiveMovesPerTargetMDB = “2″ MaxActiveMovesPerSourceServer = “50″ MaxActiveMovesPerTargetServer = “5″ MaxTotalMovesPerMRS = “100″
Essentially, these settings only allow 5 concurrent moves from the source database, 2 concurrent moves for the target database, 50 per sources server, and 5 per target server, and 100 moves per CAS server. If you are running high-end disk or have plenty of IOPS to spare, you can change the settings to:MaxActiveMovesPerSourceMDB = “15″ MaxActiveMovesPerTargetMDB = “15″ MaxActiveMovesPerSourceServer = “50″ MaxActiveMovesPerTargetServer = “40″ MaxTotalMovesPerMRS = “250″
Once changed you must restart the MRS services on the CAS server.