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There are several different tape drive and library technology available today that give companies options that will best suite their needs. A few types of tape drive and library technologies are DAT (Digital Audio Tape), DLT (Digital Linear Tape), SDLT (Super Digital Linear Tape), and LTO (Linear Tape Open) (Storage Technology and Web Base Training 1). Depending on the need of the company will depend on which technology they'll choose. .
DAT technology is basically an advancement of the audio cassettes we used to use in the past before CDs and DVDs were developed. In the mid-1980s, helical scan tape technology was adapted from home videotape technology to create DAT. DAT not only allowed for CD-quality audio recording but also produced a high-capacity backup tape technology that met the needs of mid-range and smaller systems. DAT drives employ rotating read and write head assemblies similar to a home video cassette recorder. The tape is pulled out of the cassette and wrapped around the heads that are mounted in a rapidly rotating drum. There are four heads "two write heads (opposite each other) and two read heads between them. The read heads can verify data as it is written by the write heads.
Once the tape is wrapped around the drum, the data is then recorded in diagonal stripes across the tape. This produces high capacity and relatively slow tape movement compared to DLT drives in which the tape moves but the head is stationary. During the time each write head is in contact with tape, it writes about 128KB of data and error correction codes to the tape. This data is stored in a write buffer in the tape drive. Because the cylinder is tilted in relation to the direction of travel of the tape, the head encounters one edge of the tape as it starts to write and moves diagonally across the tape to the other side, writing a narrow track that is about eight times as long as the width of the tape.
