Terabyte

From Wikipedia, the free encyclopedia

This article is about a measurement term for data storage capacity. For the fictional species, see Terabyte (insect).
Prefixes for bit and byte
Decimal
Value SI
10001 k kilo-
10002 M mega-
10003 G giga-
10004 T tera-
10005 P peta-
10006 E exa-
10007 Z zetta-
10008 Y yotta-
Binary
Value IEC JEDEC
10241 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-

A terabyte (derived from the prefix tera- and commonly abbreviated TB) is a measurement term for data storage capacity. The value of a terabyte based upon a decimal radix (base 10) is defined as one trillion (short scale) bytes, or 1000 gigabytes.

The number of bytes in a terabyte is sometimes stated to be approximately 1.0995 x 1012. This difference arises from a conflict between the long standing tradition of using binary prefixes and base 2 in the computer world, and the more popular 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 (TiB) to signify the traditional measure of 10244 bytes, or 1024 gibibytes, leading to the following definitions:

  • According to the SI standard usage, a terabyte (TB) contains 1,000,000,000,000 bytes = 10004 or 1012 bytes.
  • According to binary arithmetic, a tebibyte contains 1,099,511,627,776 bytes = 10244 or 240 bytes. Ambiguity can be reduced by avoiding the use of the term "terabyte" when the binary meaning is intended.

The capacities of computer storage devices are typically advertised using their SI standard values, but the capacities reported by software operating systems usually uses the binary values.[citation needed]

[edit] Terabytes in use

 This article needs additional citations for verification.
Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (December 2007)
  • The U.S. Library of Congress Web Capture team has claimed that "as of May 2007, the Library has collected more than 70 terabytes of data"[2]
  • Ancestry.com claims approximately 600 terabytes of genealogical data with the inclusion of US Census data from 1790 to 1930.[3]
  • YouTube offices hold over 45 terabytes of user-submitted videos[4].

[edit] See also

[edit] References

  1. ^ At Wal-Mart, World's Largest Retail Data Warehouse Gets Even Larger (2004-10-13).
  2. ^ How large is the Library’s archive? (2007-05-26).
  3. ^ Ancestry.com Adds U.S. Census Records (2006-06-22).
  4. ^ "YouTube serves up 100 million videos a day online", USA TODAY, Gannett Company, Inc, 2006-07-16. Retrieved on 2007-11-24.