Disk Redundancy
Raid is an acronym that stands for Redundant array of independent disks.
Below are some RAID configurations with a brief description.
RAID 0
Is the fastest of all the RAID levels, it uses a technique called data striping (see below) and requires at least two hard disks.
RAID 1
This level uses a pair of hard disks at a time to provide fault tolerance (there is no performance benefit) and requires at least 2 hard disks.
Using a technique called disk-mirroring (see below) the same data is written to both disks at a time, so if one hard disk crashes then the same data is available from the remaining hard disk.
RAID 2
The RAID 2 configuration uses data striping (see below) and a fault tolerance technique called parity (see below), it requires at least 3 disks.
Two (or more) of the disks are used to store the data and one disk is used to store the parity (see below) information.
RAID 2 strips the data into bits, which is why RAID 3 (below) is a better implementation as it strips the data into bytes instead.
RAID 3
A common RAID level similar to RAID 2 except that the data is striped into bytes and not bits, giving a performance benefit over RAID 2.
RAID 4
RAID 4 strips the data into blocks and uses a parity drive for fault tolerance, at least three drives are required, which are not a commonly used implementation.
RAID 5
A popular RAID configuration utilizing at least three drives.
Data is striped across the drives in bytes, the parity data for one particular drive is stored on another drive allowing the data to be rebuilt using the parity technique.
RAID 6
According to the Storage Networking Industry Association (SNIA), the definition of RAID 6 is "Any form of RAID that can continue to execute read and write requests to all of a RAID array 's virtual disks in the presence of any two concurrent disk failures”.
Works Cited
Enhance Technology, Inc. (2012). Enhance Technology. Retrieved from leveranging the benefits of RAID 6:
Below are some RAID configurations with a brief description.
RAID 0
Is the fastest of all the RAID levels, it uses a technique called data striping (see below) and requires at least two hard disks.
RAID 1
This level uses a pair of hard disks at a time to provide fault tolerance (there is no performance benefit) and requires at least 2 hard disks.
Using a technique called disk-mirroring (see below) the same data is written to both disks at a time, so if one hard disk crashes then the same data is available from the remaining hard disk.
RAID 2
The RAID 2 configuration uses data striping (see below) and a fault tolerance technique called parity (see below), it requires at least 3 disks.
Two (or more) of the disks are used to store the data and one disk is used to store the parity (see below) information.
RAID 2 strips the data into bits, which is why RAID 3 (below) is a better implementation as it strips the data into bytes instead.
RAID 3
A common RAID level similar to RAID 2 except that the data is striped into bytes and not bits, giving a performance benefit over RAID 2.
RAID 4
RAID 4 strips the data into blocks and uses a parity drive for fault tolerance, at least three drives are required, which are not a commonly used implementation.
RAID 5
A popular RAID configuration utilizing at least three drives.
Data is striped across the drives in bytes, the parity data for one particular drive is stored on another drive allowing the data to be rebuilt using the parity technique.
RAID 6
According to the Storage Networking Industry Association (SNIA), the definition of RAID 6 is "Any form of RAID that can continue to execute read and write requests to all of a RAID array 's virtual disks in the presence of any two concurrent disk failures”.
Works Cited
Enhance Technology, Inc. (2012). Enhance Technology. Retrieved from leveranging the benefits of RAID 6:
Cited: Enhance Technology, Inc. (2012). Enhance Technology. Retrieved from leveranging the benefits of RAID 6: http://www.enhance-tech.com RAID - Redundant Array of Independant Disks. (2001-2012). Retrieved from helpwithpcs : helpwithpcs.com