4 mm DAT tape drives and their use in back up devices:

A tape drive is relatively an older generation of storage technologies. DAT stands for Digital Audio Tape. The storage of digital data on these tapes gives rise to a computer data storage format known as DDS which means Digital Data Storage. Several versions of DDS were developed and some of these versions are still in use in the present day modern backup technology. 4 mm DAT drives and other DAT drives were used under DDS specification in a robust cockpit voice and flight data recorders as a black box for the flights, jets and aeroplanes. These are also used is several other applications where data storage with other technologies becomes unreliable.
A DDS tape drive uses helical scanning for recording the data. This is the same process that is used by VCR recorders. If any errors are found in the data stored, the write head rewrites the data. DDS generally uses a 3.8 mm wide tape drive for recording the data. However, in the newer versions of DDS, the tape width has been extended up to as much as 8 mm wide. Tape drives are sensitive to various physical conditions like dust and moisture. So, these tape drives must be cleaned regularly for efficient performance. Otherwise, the data stored might be at risk due to the physical destruction caused to the drive. Companies such as Seagate, HP and others manufacture these tape drives for back up storage purposes.
There are various generations of DDS specifications. Let us have a look at them.
DDS-1: This was the first generation of DDS and it is most commonly known as just DDS. This technology offered 1.3 GB of uncompressed data storage with a 60 meter long tape drive. When the data is compressed, the data stored can be doubled, that is 2.6 GB of compressed data. More data capacity can be achieved by using more length of tape.
DDS-2: This offered 4 GB uncompressed and 8 GB compressed data on a 120 meter long tape drive.
DDS-3: 12 GB uncompressed and 24 GB compressed data on 125 m drive. DDS 3 also uses advanced technology that minimises the electric noise and helps for cleaner data recording.
DDS-4 20 GB uncompressed and 40 GB compressed data on 150 m drive. Also known as DAT 40.
DAT 72: It was developed by HP and Certance. It offers 36 GB uncompressed with 72 GB compressed amount of data storage.
DAT 160 and DAT 320 are other generations which offered 80 GB and 160 GB of uncompressed data respectively. When compressed, double the amount of data can be stored. These latest devices have host interfaces for connecting through SCSI, USB and other standards.

By: Sandeep Mahanthi