You may find the technote below useful
An explanation of the "Overwrite Protection Period" and the "Append Period"
http://www.symantec.com/docs/TECH5459
Apart from granting the BESA sysadmin role in SQL, the backup exec account used for backup should have the DBO role for all SQL databases of Enterprise Vault.
To assign this role follow the steps given below:
1) On the SQL server open the Microsoft S...