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PC Hardware in a Nutshell, 3rd Edition by Barbara Fritchman Thompson, Robert Bruce Thompson

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Tape Technologies

Four tape technologies compete in the PC and small server markets:

Quarter Inch Cartridge (QIC)

Originally developed in the early 1970s, two styles of QICs have been made. The physically larger DC600 cartridge is obsolete. Recent QIC tape drives use DC2000 minicartridges, which have been made in capacities from 400 MB to 20 GB. QIC drives use serpentine recording, which records many parallel tracks on each tape. The drive records data from the beginning to the end of the first track, reverses direction, writes data from the end to beginning of the second track, and so on, until all tracks have been written. This means that filling a tape may require more than 100 passes of the tape through the drive, which increases wear and tear on both drive and tape. Some recent QIC drives have the extra head required for read-while-write, which allows the drive to back up and compare data in one pass. Doing a compare on a single-head drive doubles the number of passes required, and extends backup time significantly.

Current QIC drives use Travan technology, a combination of tape and drive technologies developed by 3M/Imation, and now implemented by many drive manufacturers. Travan-NS (Network Solution) drives provide read-while-write verification and hardware compression, which allows the drive to compress data as it writes it, rather than depending on compression performed by the backup software. The most recent Travan technology, called Travan 40, is targeted at desktop ...

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