 - Also see Kibi, mebi, gibi, tebi, pebi, and all that, which are relatively new prefixes designed to express power-of-two multiples.
Kilo, mega, giga, tera, and peta are among the list of prefixes that are used to denote the quantity of something, such as, in computing and telecommunications, a byte or a bit. Sometimes called prefix multipliers, these prefixes are also used in electronics and physics. Each multiplier consists of a one-letter abbreviation and the prefix that it stands for.
In communications, electronics, and physics, multipliers are defined in powers of 10 from 10-24 to 1024, proceeding in increments of three orders of magnitude (103 or 1,000). In IT and data storage, multipliers are defined in powers of 2 from 210 to 280, proceeding in increments of ten orders of magnitude (210 or 1,024). These multipliers are denoted in the following table.
| Prefix |
Symbol(s) |
Power of 10 |
Power of 2 |
| yocto- |
y |
10-24 * |
-- |
| zepto- |
z |
10-21 * |
-- |
| atto- |
a |
10-18 * |
-- |
| femto- |
f |
10-15 * |
-- |
| pico- |
p |
10-12 * |
-- |
| nano- |
n |
10-9 * |
-- |
| micro- |
m |
10-6 * |
-- |
| milli- |
m |
10-3 * |
-- |
| centi- |
c |
10-2 * |
-- |
| deci- |
d |
10-1 * |
-- |
| (none) |
-- |
100 |
20 |
| deka- |
D |
101 * |
-- |
| hecto- |
h |
102 * |
-- |
| kilo- |
k or K ** |
103 |
210 |
| mega- |
M |
106 |
220 |
| giga- |
G |
109 |
230 |
| tera- |
T |
1012 |
240 |
| peta- |
P |
1015 |
250 |
| exa- |
E |
1018 * |
260 |
| zetta- |
Z |
1021 * |
270 |
| yotta- |
Y |
1024 * |
280 |
| * Not generally used to express data speed |
| ** k = 103 and K = 210 |
Examples of quantities or phenomena in which power-of-10 prefix multipliers apply include frequency (including computer clock speeds), physical mass, power, energy, electrical voltage, and electrical current. Power-of-10 multipliers are also used to define binary data speeds. Thus, for example, 1 kbps (one kilobit per second) is equal to 103, or 1,000, bps (bits per second); 1 Mbps (one megabit per second) is equal to 106, or 1,000,000, bps. (The lowercase k is the technically correct symbol for kilo- when it represents 103, although the uppercase K is often used instead.)
When binary data is stored in memory or fixed media such as a hard drive, diskette, ZIP disk, tape, or CD-ROM, power-of-2 multipliers are used. Technically, the uppercase K should be used for kilo- when it represents 210. Therefore 1 KB (one kilobyte) is 210, or 1,024, bytes; 1 MB (one megabyte) is 220, or 1,048,576 bytes.
The choice of power-of-10 versus power-of-2 prefix multipliers can appear arbitrary. It helps to remember that in common usage, multiples of bits are almost always expressed in powers of 10, while multiples of bytes are almost always expressed in powers of 2. Rarely is data speed expressed in bytes per second, and rarely is data storage or memory expressed in bits. Such usages are considered improper. Confusion is not likely, therefore, provided one adheres strictly to the standard usages of the terms bit and byte.
 |
Learn more about Disk arrays |
| No-maintenance disk array aims to eliminate hard drive swapping: SAID (Sealed Array of Identical Disks) array from startup Atrato bridges the performance-capacity gap. It can in theory run for the term of a 5-year lease with zero maintenance. |
| Fail-in-place systems: Avoiding hard disk drive failures: Fail-in-place storage systems, such Atrato's V1000 and Xiotech's Emprise 5000 or ISE, can virtually eliminate hard disk drive replacement service calls. |
| Multiprotocol storage arrays gain interest, adoption: Multiprotocol storage arrays, or unified storage, combine block and file storage access protocols. Interest due to cost savings, advances in technology and simpler management. |
| Enterprise disk array consolidation product specifications: Knowing the purchasing criteria for enterprise-class disk arrays, as well as product specs for the leading arrays, can help storage managers make savvy buying decisions. |
| What is a terabyte? What is bigger than a terabyte?: What is a terabyte? What are terabytes? What are terabyte drives? What comes after a terabyte? What's bigger than a terabyte? Please don't just say that 2 terabytes is bigger than one terabyte. |
| Virtual storage via HDS USP VM disk array helps Canadian city upgrade to VMware ESX Server 3.5: City of Coquitlam, B.C., encounters no major obstacles in virtual storage implementation as part of an upgrade to an HDS USP VM disk array and VMware ESX Server 3.5. |
| Data deduplication and compression on primary storage can reduce data footprint: Deduplication and compression on primary storage may not produce the data reduction seen with backups, but various techniques produce significant results with unstructured data. |
| Storwize claims good data compression rates, no performance degradation on STN-6000 appliance: Storwize's STN-6000 inline appliance acts on primary storage using real-time compression. |
| NetApp: Post-process deduplication limits performance hit in primary storage data deduplication: NetApp's approach to primary storage data deduplication limits the performance penalty to about 20% percent. |
| Best practices for solid-state drive storage technology: SSD best practices center on identifying I/O-intensive applications so that data storage technology can provide the greatest benefit to IT organizations. |
| CONTRIBUTORS: |
David Gabel |
| LAST UPDATED: |
10 Sep 2010
|
 |
Do you have something to add to this definition? Let us know.
Send your comments to techterms@whatis.com
|
|
More resources from around the web:
|
 |
 |
| |
RELATED GLOSSARY TERMS
| Terms from Whatis.com − the technology online dictionary |
 |
array
(SearchStorage.com)
In general, an array is a number of items arranged in some specified way - for example, in a list or in a three-dimensional table.
|
|
array-based memory
(SearchStorage.com)
Array-based memory is an evolving solid-state storage technology similar to flash memory but with potentially greater storage capacity. The increased...
|
|
|
Show me everything on 
