Storage capacity is crucial to the operation of a database management system. Even the many megabytes of hard disk storage in a efficient, modern microcomputer system can’t handle the many gigabytes of data that move through some large corporations. However, not all organizations that moves through some large corporations. However, not all organizations need minicomputer- or mainframe-based database management systems. Recent advances in the speed and capacity of hard disk drives for microcomputers-plus the use of CD-ROM drives- have made microcomputer-based database management systems possible of some organizations.
Because database files represent an important business resource, they must be protected from damage, loss and unauthorized use. The most common way to protect the corporate database from loss or damage is to periodically make backup copies of it. In large database systems, backup copies are usually made on one or more cartridges of magnetic tape. The backup process for large corporate databases requires the involvement of computer operations specialists. The most popular form of backup for microcomputer hard disks is the tap streamer, or streaming tap unit, which is also available in cartridges. These devices are small, fast, and so easy to use that the user can perform the backup operation unassisted.