You should perform a backup as often as practical, balancing the amount of data loss in a failure situation against the interruption to production that a backup causes. To achieve this balance, consider these points:

In cases where data is backed up once a day, it is possible to lose the work of an entire day if the disks fail or a natural disaster strikes at the end of the day. If you perform multiple backups throughout the day but only archive once a day, you are be better protected from a hardware, software, or user error, but your protection from most natural disasters is identical. By moving the intra-day tapes from the computer room to a different area of your facility, you decrease the probability of a fire in the computer room destroying your tapes.