I have the same issue. When I run a backup I get the error "Backup Exec could not back up the Exchange database because it could not find a healthy copy of the database." The backup server is a new windows 2008 R2 64-bit server with all patches. The exchange are new windows 2008 R2 servers with all patches. I have 2 Exchange 2010 CAS/HT servers load balanced behind an F5 and 2 Exchange 2010 mailbox role servers. The DAG's show as Mounted and Healthy. The servers are all in the same subnet so no ACL issues. All patches have been applied, all servers have been restarted multiple times, I get no errors on the test of creditials and the license is installed. Any idea's?