At one time, tapes were the standard backup medium – they were inexpensive, making it cheaper to perform daily server backup. But tape isn't a random access medium. You cannot jump to a specific file or folder because data has to be accessed exactly as it was written to tape. In order to recover specific data from tape, IT administrators have to spool forward or backward to reach the information that must be restored – a process that can take hours, or even days.
Tape is also much less robust than disk-based media, due to its nature. Just as an audio cas-sette degrades over time, so does tape backup. Over a short period of time, the cost savings that may have been gained by using tape media rather than disk media is eliminated.
In order to perform a complete backup of an entire computing environment, it takes many hours to write all of the data to tape. This creates large backup windows – time when the server cannot be in use because each file must be closed in order to complete a proper backup.
It's no wonder that recent studies also show that most IT administrators don't feel comfort-able with their tape backups.