Digital Data Storage (DDS) is a format for storing and backing up computer data on magnetic tape that evolved from Digital Audio Tape (DAT) technology, which was originally created for CD-quality audio recording. In 1989, Sony and Hewlett Packard defined the DDS format for data storage using DAT tape cartridges. Tapes conforming to the initial DDS format can be "played" by either DAT or DDS tape machines. However, most DDS tape drives cannot retrieve the audio stored on a DAT cartridge. 1989 (MCMLXXXIX) was a common year starting on Sunday of the Gregorian calendar. ... 1993 (MCMXCIII) was a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ... 1996 (MCMXCVI) was a leap year starting on Monday of the Gregorian calendar, and was designated the International Year for the Eradication of Poverty. ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Older Persons by the United Nations. ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A computer is a machine designed for manipulating data according to a list of instructions known as a program. ... Data is the plural of datum. ... Compact audio cassette Magnetic tape is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The Compact Disc logo was inspired by that of the previous Compact Cassette. ... 1989 (MCMLXXXIX) was a common year starting on Sunday of the Gregorian calendar. ... Sony Corporation ) is a Japanese multinational corporation and one of the leading manufacturers of video, communications, and information technology products for the consumer and professional markets. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

DDS uses 4 millimeter (more accurately: 3.8 mm) wide tape. Initially, the tape was 60 or 90 meter long, although advancements in materials technology has allowed the length to be increased significantly in successive versions. A DDS tape drive uses helical scanning for recording, the same process used by a video cassette recorder (VCR). There are two read heads and two write heads. The read heads verify the data that has been written (recorded). If errors are present, the write heads rewrite the data. A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... The metre, or meter (symbol: m) is the SI base unit of length. ... The video cassette recorder (or VCR, less popularly video tape recorder) is a type of video tape recorder that uses removable cassettes containing magnetic tape to record audio and video from a television broadcast so it can be played back later. ...

A DDS cartridge needs to be retired after 2,000 passes or 100 full backups. Tape drives should be cleaned regularly to be kept in good working order. DDS tapes have an expected life of at least 10 years.

A DDS-1/DAT cassette

Image File history File linksMetadata Download high resolution version (1812x1262, 855 KB) Summary Licensing File links The following pages link to this file: Digital Data Storage Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ... Image File history File linksMetadata Download high resolution version (1812x1262, 855 KB) Summary Licensing File links The following pages link to this file: Digital Data Storage Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ...

DDS-1

Stores up to 1.3 GB uncompressed (2.6 GB compressed) on a 60 meter cartridge, 2 GB uncompressed (4GB compressed) on a 90 meter cartridge.

DDS-2

Stores up to 4 GB uncompressed (8 GB compressed) on a 120 meter cartridge.

DDS-3

Stores up to 12 GB uncompressed (24 GB compressed) on a 125 meter cartridge. DDS-3 uses PRML (Partial Response Maximum Likelihood). PRML eliminates electronic noise for a cleaner data recording.

DDS-4

DDS-4 stores up to 20 GB uncompressed (40 GB compressed) on a 150 meter cartridge.

DAT 72

DAT72 stores up to 36 GB uncompressed (72 GB compressed) on a 170 meter cartridge. The DAT 72 standard was developed by HP and Certance. It has the same form-factor and is backwards compatible with DDS-3 and -4. The data transfer rate was hoped to be around 7 MB/s. Certance was the former tape drive division of Seagate. ...

Image File history File links Dat_72. ... Image File history File links Dat_72. ...

DAT 160

HP was asked if the DAT 160 schedule is on track for the end of the year. Chris Sopp, HP's European tape product marketing manager, said DAT 160 will arrive in the first three months of 2006. It will use a wider tape than DAT 72 but drives will be able to read DAT 72 tapes because there will be two load mechanisms. It will also have a USB connection as well as a parallel SCSI one.

He sais that it was possible the next DAT drive, the DAT 320, will have a serial-attached SCSI (SAS) connection when it arrives.

External links

• DAT Manufacturers Group
• Using Audio DATs in DDS drives
• A brief history of tape (pdf)