Magnetic tape uses a method similar to that of VCR tape for storing data.
The speed of access can be quite slow, however, when the tape is long and what you want is not near the start. So this method is used primarily for major backups of large amounts of data.
Businesses especially might do a backup of the day's transactions every day and a backup of the whole system once a week or so. Keeping sets of backups like this minimizes the amount of data loss when the computer system goes down.
Each different tape storage system has its own requirements as to the size, the container type, and the magnetic characteristics of the tape. Older systems designed for networks use reel-to-reel tapes. Newer systems use cassettes. Some of these are even smaller than an audio cassette but hold more data than the huge reels. Even if they look alike, the magnetic characteristics of tapes can vary. It is important to use the tape that is right for the system.
|Tape Reel||Tape Cassette|
Just as hard disks have several different formats, so do magnetic tapes. The format method will determine the following characteristics.
Higher density means more data on shorter tape
The tape is divided into logical blocks, as a hard disk is divided into tracks and sectors. One file could take up many logical blocks, but must take up at least one whole block. So smaller blocks would result in less wasted space, leaving more room for data.
Two kinds of blank spots, called gaps, are set on the tape.