We migrated to Windows 2008 R2 server and Exchange 2010. All Outlook client are connected to 2010 server and functioning. New 2008 R2 server is Global Catalog server and all FSMO rolls have been transferred. If we down old server and reboot new server Exchange Information Store service (and a few others Exchanges services) will loop on starting and stopping. As soon as we boot old server the Exchange Information Store service starts and all works. At some point in the future we will demote old server. My concern is if old server fails or I demote it will my Exchange 2010 stop working.