extends RAID 5 by adding another parity block

 extends RAID 5 by adding another parity block

RAID

 

·         (redundant array of independent disks) configurations that employ the techniques of striping, mirroring, or parity to create large reliable data stores from multiple general-purpose computer hard disk drives (HDDs).

 

RAID 0

 

·         (also known as a stripe set or striped volume) splits ("stripes") data evenly across two or more disks, without parity information, redundancy, or fault tolerance.

 

the failure of one drive will cause the entire array to fail; as a result of having data striped across all disks, the failure will result in total data loss.

 

·         RAID 0

 

This configuration is typically implemented having speed as the intended goal.

 

·         RAID 0

 

RAID 1

 

·         consists of an exact copy (or mirror) of a set of data on two or more disks, This configuration offers no parity, striping, or spanning of disk space across multiple disks, since the data is mirrored on all disks belonging to the array, and the array can only be as big as the smallest member disk.

 

This layout is useful when read performance or reliability is more important than write performance or the resulting data storage capacity.

 

·         RAID 1

 

RAID 2

 

·         which is rarely used in practice, stripes data at the bit (rather than block) level, and uses a Hamming code for error correction.

 

has been rarely implemented; it is the only original level of RAID that is not currently used.

 

·         RAID 2

 

RAID 3

 

·         which is rarely used in practice, consists of byte-level striping with a dedicated parity disk. One of the characteristics of RAID 3 is that it generally cannot service multiple requests simultaneously, which happens because any single block of data will, by definition, be spread across all members of the set and will reside in the same location.

 

Applications that make small reads and writes from random disk locations will get the worst performance out of this level.

 

·         RAID 3

 

RAID 4

 

·         consists of block-level striping with a dedicated parity disk.

 

As a result of its layout, this raid level provides good performance of random reads, while the performance of random writes is low due to the need to write all parity data to a single disk

 

·         RAID 4

 

RAID 5

 

·         consists of block-level striping with distributed parity. Unlike in RAID 4, parity information is distributed among the drives.

 

requires that all drives but one be present to operate. Upon failure of a single drive, subsequent reads can be calculated from the distributed parity such that no data is lost.

 

·         RAID 5

 

RAID 6

 

·         extends RAID 5 by adding another parity block; thus, it uses block-level striping with two parity blocks distributed across all member disks.