Scheduled Service Change: Update Exchange 2010 to Rollup5
Individuals who are using Exchange during the Sunday updates may notice an extremely brief (less than 10 seconds) interruption in their connection.\n\nCAS/Hubs will be patched 2/time leaving 4 available for use, and the mailbox pairs will be handled one machine/pair at a time with the database failover happening before patching begins. Outage for the failover should be less than 10 seconds from the user's POV.
There is no workaround for this issue
Apply Rollup 5 for Exchange 2010 on Sunday, October 2, and Sunday, October 9, from 8-11 am. The update fixes several issues that some users may have noticed.