12.2 Backup Media
12.2.1 Magnetic tape
There are a number of different media options for backing up your data. They range from very low capacity floppy disks to very high capacity tape drives. Streaming magnetic tape is the most common media for backing up large amounts of data. Tape drives are sequential recording devices which means that the data is laid down in a stream of bits from one end to the other as the tape passes the magnetic read/write heads. To locate a specific file on a tape, it must be rewound or advanced to the location where the file was recorded. This can take several minutes depending on the speed of the drive and where the file is located. In spite of this, modern tape drives will continue to be widely used since they are efficient, cost effective, and a proven backup solution. Today's new technology tape drives are small, very fast and have very large recording capacities. The cost per megabyte for tape backup is the lowest of any recording media. A single tape about the size of a video cassette can record over 100GB (Gigabytes or billion bytes) of data with compression. Autoloader systems with multiple tapes can exceed that significantly.