Tape backup can refer to any system that uses a magnetic tape as the backup medium. The backup can be either an entire disk drive, or just a smaller group of files as selected by the user or system administrator. The backup can be made manually, or can be scheduled to occur automatically, assuming the tape backup software has that capability.
The tape “drive” can be a single cartridge tape unit, where the cartridges are handled by the user, one at a time. These types of systems are normally used in small business environments, and in some cases by personal computer users.
For “enterprise class” tape backup solutions, a tape “library” is more common. This is a large device that holds tens or hundreds of tape cartridges and has a robotic system that moves the tapes from a storage location in the cabinet, to the “drive” section of the library.
Tape libraries are relatively expensive and are usually shared by many computers and are connected to those systems through a network of some kind. This network can be either an Ethernet-based network or a SAN (Storage Area Network).
The advantage to having tape backup is that the tapes can be physically stored away from the facility where they are made, so that if there is a fire, or other disaster (flood, earthquake, etc), then these tapes can be used to restore the data that is backed up. The disadvantage to having backup tapes is that the process of restoring the information can be slow. And unless the actual tapes are not replaced on a regular basis (they have a limited lifetime) and a “test” restore is not done every few months, then the reliability of this system would be in question. That is why “backup” and “restore” should always be considered together.