Creating a New Media Set
To create a new media set, you must format the backup media (one or more tapes or disk files). The formatting process changes the backup media as follows:
Deletes the old header (if any), effectively deleting the previous contents of the backup media.
Formatting a tape device deletes all previous contents of the currently mounted tape. Formatting a disk affects only the file that you specify for the backup operation
Writes a new media header on the backup media (tape or disk file) on each of the backup devices.
To create a new media set by using Transact-SQL
To create a new media set, use the FORMAT option of the BACKUP statement.
To create a new media set by using SQL Server Management Studio
To create a new media set, erasing any existing media header and backup sets, select Back up to a new media set, and erase all existing backup sets on the Options page of the Back Up Database dialog box.
To create a new media set by using SQL Server Management Objects (SMO)