Digital Data Storage

Computer data storage technology based on magnetic tape

This article is about a particular technology. For the general concept, see Computer data storage.

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Digital Audio Tape

Media type| Magnetic cassette tape
Encoding| Lossless real-time
Read mechanism| Rotating head
Write mechanism| Rotating head, helical scan
Developed by| Sony
Usage| Data storage
Extended from| Digital Audio Tape
Released| 1989; 36 years ago (1989)

Digital Data Storage (DDS) is a computer data storage technology that is based upon the Digital Audio Tape (DAT) format that was developed during the 1980s. DDS is primarily intended for use as off-line storage, especially for generating backup copies of working data.

## Design

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A DDS cartridge uses tape with a width of 3.81mm, with the exception of the latest formats, DAT-160 and DAT-320, both which use 8mm wide tape. Initially, the tape was 60 meters (197 feet) or 90 meters (295 ft.) in length. Advancements in materials technology have allowed the length to be increased significantly in successive versions. A DDS tape drive uses helical scan recording, the same process used by a video cassette recorder (VCR).

Backward compatibility between newer drives and older cartridges is not assured; the compatibility matrices provided by manufacturers will need to be consulted.[1] Typically drives can read and write tapes in the prior generation format, with most (but not all) also able to read and write tapes from two generations prior. Notice in HP's article that newer tape standards do not simply consist of longer tapes; with DDS-2, for example, the track was narrower than with DDS-1.

At one time, DDS competed against the Linear Tape-Open (LTO), Advanced Intelligent Tape (AIT), VXA, and Travan formats. However, AIT, Travan and VXA are no longer mainstream, and the capacity of LTO has far exceeded that of the most recent DDS standard, DDS-320.

## History

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This section is in list format but may read better as prose. You can help by converting this section, if appropriate. Editing help is available. (August 2021)

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A DDS-2 cartridge. DDS Streamer inside DDS Cartridges A DAT 72 cartridge DAT 160 logo DAT-72 tape drive, front panel

DDS-1
Stores up to 1.3 GB uncompressed (2.6 GB compressed) on a 60 m cartridge or 2 GB uncompressed (4 GB compressed) on a 90 m cartridge. The DDS-1 cartridge often does not have the -1 designation, as initially it was the only format, though cartridges produced since the introduction of DDS-2 may carry a -1 designation to distinguish the format from newer formats. A media recognition system was introduced with DDS-2 drives and cartridges to detect the medium type and prevent the loading of an improper medium. From 1993, DDS-1 tapes included the media recognition system marks on the leader tape—a feature indicated by the presence of four vertical bars after the DDS logo.
DDS-2
Stores up to 4 GB uncompressed (8 GB compressed) on a 120 m cartridge.
DDS-3
Stores up to 12 GB uncompressed (24 GB compressed) on a 125 m cartridge. DDS-3 uses PRML (Partial Response Maximum Likelihood) to minimize electronic noise for a cleaner data recording.
DDS-4
DDS-4 stores up to 20 GB uncompressed (40 GB compressed) on a 150 m cartridge. This format is also called DAT 40.
DAT 72
DAT 72 stores up to 36 GB uncompressed (72 GB compressed) on a 170 m cartridge. The DAT 72 standard was developed by HP and Certance. It has the same form-factor as DDS-3 and -4 and is sometimes referred to as DDS-5.
DAT 160
DAT 160 was launched in June 2007 by HP, stores up to 80 GB uncompressed (160 GB compressed). A major change from the previous generations is the width of the tape. DAT 160 uses 8 mm wide tape in a slightly thicker cartridge while all prior versions use 3.81 mm wide tape. Despite the difference in tape widths, DAT 160 drives can load DAT-72 and DAT-40 (DDS-4) cartridges. Native capacity is 80 GB and native transfer rate was raised to 6.9 MB/s, mostly due to prolonging head/tape contact to 180° (compared to 90° previously).[2] Launch interfaces were Parallel SCSI and USB, with SAS interface released later.
DAT 320
In November 2009 HP announced the DAT-320 standard, which stores up to 160 GB uncompressed (marketed as 320 GB assuming 2:1 compression) per cartridge. Native transfer rate was raised to 12 MB/s.

### Generations

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DDS generations  Format  | Date  | Tape
width
(mm)  | Track
pitch
(μm)  | Tape
length
(m)  | Native
capacity
(GB)  | Capacity assuming
2:1 compression
(GB)  | Drum rotation
speed
(RPM)  | Data transfer
speed
(MB/s)

|
|
|
|
|
|
|
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DDS-1  | 1989  | 3.81  | 13.6  | 60/90  | 1.3/2.0  | 2.6/4  | 2000, 2551  | 0.183
DDS-2  | 1993  | 3.81  | 9.1  | 120  | 4.0  | 8  | 4000, 4400, 5737, 8500  | 0.360-0.720
DDS-3  | 1996  | 3.81  | 9.1  | 125  | 12.0  | 24  | 3825, 4252  | <1.5
DDS-4  | 1999  | 3.81  | 6.8  | 150  | 20.0  | 40  | 11400  | 1.0-3.2
DAT-72  | 2003  | 3.81  | 5.4  | 170  | 36.0  | 72  | 8609.7, 10000  | 3.2
DAT-160  | 2007  | 8  | 6.8  | 154  | 80  | 160  | 6457  | 6.9
DAT-320  | 2009  | 8  |  | 153[3] | 160  | 320  |  | 12
(Gen 8)  | canceled  | 8  |  |  | ~300  | ~600  |  | ≥16

### Future

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The next format, Gen 8, was canceled.[citation needed]

## See also

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* Data8
* Magnetic storage

## References

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1. ^ Compatibility matrix for: HP, IBM
2. ^ "DAT Technology". DAT Manufacturers Group. Archived from the original on 2013-05-31. Retrieved 2013-03-31.`{{cite web}}`: CS1 maint: bot: original URL status unknown (link)
3. ^ "HP DAT 320 320GB Data Cartridge - DAT & DDS tape cartridges - HP: Q2032A". Hewlett-Packard. Archived from the original on 2014-01-01. Retrieved 2013-12-31.

## External links

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Wikimedia Commons has media related to Digital Data Storage.

* DAT Manufacturers Group
* ECMA-139 ISO/IEC 10777:1991, Specification of DDS. ECMA-139
* ECMA-146 ISO/IEC 11321:1992, Specification of DATA/DAT. ECMA-146
* ECMA-150 ISO/IEC 11557:1992, Specification of DDS-DC (DDS w/ compression). ECMA-150
* ECMA-151 ISO/IEC 11558:1992, Specification of DCLZ (compression algorithm). ECMA-151
* ECMA-170 ISO/IEC 12447:1993, Specification of DDS (for 60m and 90m tapes). ECMA-170
* ECMA-171 ISO/IEC 12448:1993, Specification of DATA/DAT-DC (for 60m and 90m tapes). ECMA-171
* ECMA-198 ISO/IEC 13923, Specification of DDS-2. ECMA-198
* ECMA-236 ISO/IEC 15521, Specification of DDS-3. ECMA-236
* ECMA-288 ISO/IEC 17462, Specification of DDS-4. ECMA-288

* v
* t
* e

Magnetic-tape data storage formats

Linear|

| Wide (19–25.4 mm)|

* IBM 7340 (1961)
* LINCtape (1962)
* DECtape (1963)
* CDC 626 (1966)

|

Half inch (12.7 mm)|

* UNISERVO (1951)
* IBM 7-track (1952)
* TX-2 Tape System (1958)
* 9-track (1964)
* IBM 3480 (1984)
* DLT (1984)
* IBM 3590 (1995)
* T9840 (1998)
* T9940 (2000)
* LTO Ultrium (2000)
* IBM 3592 (2003)
* T10000 (2006)

Eight millimeter (8 mm)|

* Travan (1995)
* IBM 3570 MP (1997)
* ADR (1999)

Quarter inch (6.35 mm)|

* QIC (1972)
* SLR (1986)
* Ditto (1992)

"Eighth" (0.15) inch (3.81 mm)|

* D/CAS (1971)
* KC standard, Compact Cassette (1975)
* DC100 (1976)
* Tarbell Cassette Interface (1976)
* Commodore Datasette (1977)
* DECtape II (1979)
* IBM PC Cassette (1981)

Stringy (1.58–1.9 mm)|

* Exatron Stringy Floppy (1979)
* ZX Microdrive (1983)
* QL Microdrive (1984)
* Rotronics Wafadrive (1984)

Helical|

| Three quarter inch (19 mm)|

* Sony DIR (19xx)
* Ampex DST (1992)

|

Half inch (12.7 mm)|

* ArVid (1992)
* Redwood SD-3 (1995)
* DTF (19xx)
* SAIT (2003)

Eight millimeter (8 mm)|

* Data8 (1987)
* Mammoth (1994)
* AIT (1996)
* VXA (1999)

Four millimeter (3.81 mm)|

* DDS/DAT (1989)

* v
* t
* e

Standards of Ecma International

Application interfaces|

* ANSI escape code
* APIW
* Common Language Infrastructure
* Office Open XML
* OpenXPS

File systems (tape)|

* Advanced Intelligent Tape
* DDS
* DLT
* Super DLT
* Linear Tape-Open (Ultrium-1)
* VXA

File systems (disk)|

* CD-ROM
* CD File System (CDFS)
* FAT
* FAT12
* FAT16
* FAT16B
* FD
* UDF
* Ultra Density Optical
* Universal Media Disc
* Holographic Versatile Disc

Graphics|

* Universal 3D

Programming languages|

* C++/CLI
* C#
* Eiffel
* JavaScript (E4X, ECMAScript)
* Dart
* Minimal BASIC
* Full BASIC

Radio link interfaces|

* NFC
* UWB

Other|

* ECMA-35
* JSON

List of Ecma standards (1961 – present)
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*[e]: Edit this template