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parity

 
Dictionary: par·i·ty2   (păr'ĭ-tē) pronunciation
 
Home > Library > Literature & Language > Dictionary
n.
  1. The condition of having given birth.
  2. The number of children borne by one woman.

[Latin parere, to give birth, bring forth + –ITY.]


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Computer Desktop Encyclopedia: RAID
 
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(Redundant Array of Independent Disks) A disk subsystem that increases performance or provides fault tolerance or both. RAID uses two or more hard drives and a RAID controller, which is plugged into motherboards that do not have built-in RAID circuits. Today, most motherboards have RAID built in. In the past, RAID was also accomplished by software only, but was much slower. In the late 1980s, the "I" in RAID stood for "inexpensive," but was later changed to "independent."

In large storage area networks (SANs), floor-standing RAID units are common with terabytes of storage and huge amounts of cache memory. RAID is also used in desktop computers by gamers for speed and by business users for reliability. Following are the various RAID configurations. See NAS and SAN.

RAID 0 - Disk Striping for Performance (Popular)

Widely used for gaming, disk striping interleaves data across multiple drives for performance. However, there are no safeguards against failure.

RAID 1 - Mirroring for Fault Tolerance (Popular)

Widely used, mirroring writes two drives at the same time so that data are duplicated. It provides the highest reliability, but doubles the number of drives needed.

RAID 10 (RAID 1+0)

RAID 10 combines RAID 1 and RAID 0. Drives are mirrored for fault tolerance (RAID 1) and striped for performance (RAID 0). For more speed, RAID 100 combines RAID 10 and 0. It adds a layer of striping (RAID 0) on top of two or more RAID 10 configurations.

RAID 3 - Speed and Fault Tolerance

Data are striped across three or more drives. Used to achieve the highest data transfer because all drives operate in parallel. Using byte level striping, parity bits are stored on separate, dedicated drives. Similar to RAID 3, RAID 4 uses block level striping, but is not as popular. For more on parity computations, see RAID parity.

RAID 5 - Speed and Fault Tolerance (Popular)

Data are striped across three or more drives for performance, and parity bits are used for fault tolerance. The parity bits from two drives are stored on a third drive and are interspersed with user data. RAID 5 is widely used in servers.

RAID 6 - Speed and Fault Tolerance

Similar to RAID 5 but performs two parity computations or the same computation on overlapping subsets of the data. Highest reliability because it can recover from two failed disks, but not widely used.

Big RAID
EMC has been a leader in high-end RAID systems for years with systems storing multiple terabytes of data. (Image courtesy of EMC Corporation.)

Little RAID
Arco was the first to provide RAID 1 mirroring on inexpensive IDE drives rather than SCSI. This unit took up two drive bays and connected to one Parallel ATA (PATA) cable like a single drive. (Image courtesy of Arco Computer Products, Inc., www.arcoide.com)

Early RAID
This RAID prototype was built by University of Berkeley graduate students in 1992. Housing 36 320MB disk drives, total storage was 11GB. (Image courtesy of The Computer History Museum, www.computerhistory.org)

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Medical Dictionary: par·i·ty
Top
Home > Library > Health > Medical Dictionary
(păr'ĭ-tē)
n.

The state of having given birth to an infant or infants.

 
Wikipedia: Parity (medicine)
Top
Home > Library > Miscellaneous > Wikipedia
 This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed. (January 2008)
For other uses of the term in other fields, see parity.

In medicine, parity is a technical term that refers to the number of times a woman or female animal has given birth. A woman who has given birth a particular number of times is referred to as para 0, para 1, para 2, para 3 and so on.

  • A woman who has never completed a pregnancy beyond 20 weeks is referred to as being nulliparous, a nullipara or para 0. [1]
  • A woman in her first pregnancy can also be referred to as being primipara which can be shortened to primip.
  • Biparous or bipara are sometimes used as synonyms for para 2.
  • A woman who has given birth two or more times is referred to as multiparous or just as a multip. The term multiparous can also describe a birth of more than one offspring at once, in contrast to a uniparous birth of one offspring.
  • Grand multipara refers to a (grand multiparous) woman who has given birth five or more times.

Parity is recorded in the format, T-P-A-L:

T 
is the number of term births
P 
is the number preterm births
A 
is the number of abortions (spontaneous or induced)
L 
is the number of living children.

For example, parity of a woman who has given birth at term once and has had one miscarriage would be recorded as P 1-0-1-1. This notation is not standardized and can lead to misinterpretations. [1]

Term births are those occurring at 37 weeks or beyond. Preterm births are those that occur before 37 weeks.

References

  1. ^ a b F. Gary Cunningham, 2005. Williams Obstetrics, 22nd Edition, McGraw-Hill Companies.

See also

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Computer Desktop Encyclopedia. THIS COPYRIGHTED DEFINITION IS FOR PERSONAL USE ONLY.
All other reproduction is strictly prohibited without permission from the publisher.
© 1981-2009 Computer Language Company Inc.  All rights reserved.  Read more
Medical Dictionary. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company.  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Parity (medicine)".  Read more

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