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A terabyte is a SI-multiple (see prefix tera-) of the unit byte for digital information storage and is equal to 1012 (1000000000000bytes) or 1000 gigabytes. The terabyte is abbreviated with the symbol TB.

Prefixes for bit and byte multiples
Value SI
1000 k kilo-
10002 M mega-
10003 G giga-
10004 T tera-
10005 P peta-
10006 E exa-
10007 Z zetta-
10008 Y yotta-
1024 Ki kibi- K kilo-
10242 Mi mebi- M mega-
10243 Gi gibi- G giga-
10244 Ti tebi-
10245 Pi pebi-
10246 Ei exbi-
10247 Zi zebi-
10248 Yi yobi-

The designation terabyte is rarely used to refer to the tebibyte, its binary prefix analogue, because only recent (since 2007) disk drives reach this capacity. Disk drive sizes are always designated in SI units by manufacturers. However, a possible confusion arises from a conflict between the long-standing tradition of using binary prefixes and base 2 for memory sizes, and the decimal (SI) standard adopted widely both within and outside of the computer industry. Standards organizations such as IEC, IEEE and ISO recommend to use the alternative term tebibyte to signify the traditional measure of 10244 bytes, or 1024 gibibytes, leading to the following definitions:

  • According to the SI standard usage, 1 terabyte (TB) equals 1000000000000bytes = 10004 or 1012 bytes.
  • Using the traditional binary interpretation, a terabyte is 1099511627776bytes = 10244 or 240 bytes = 1 tebibyte (TiB).

The capacities of computer storage devices are typically advertised using their standard SI values, but some operating systems report in binary-based values.

[edit] Examples of terabyte storage

  • The U.S. Library of Congress Web Capture team has claimed that "as of May 2008, the Library has collected more than 82.6 terabytes of data".[1]
  • Ancestry.com claims approximately 600 TB of genealogical data with the inclusion of US Census data from 1790 to 1930.[2]
  • Hitachi introduced the world's first one terabyte hard disk drive in 2007.[3]
  • In 1993, total Internet traffic amounted to approx. 100 TB for the year.[4] As of June 2008, Cisco Systems estimated Internet traffic at 160 TB/s (which equals about 5 Zettabytes for the year).[5]

[edit] See also

[edit] References

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