RAID 2

From ProPHOTO WIKI

Introduction

A rarely used RAID variation, RAID 2 stripes data across a number of drives at the bit level and uses a hamming code to add parity information for redundancy purposes (similar to RAID 3). Unfortunately, these arrays are complicated and often require large numbers of drives to implement (14+) so they aren't suitable for simple configurations. Because of this complexity, RAID 2 quickly became eclipsed by the more efficient arangement used in RAID levels 3 through 6 (all of which can be scaled up to provide similar performance) and is not used in any modern RAID implementations. As it is unlikely that anyone reading this will ever run into a RAID 2 drive array, further discussion is beyond the scope of this document.

See Also

• RAID - General overview of RAID and all of its different levels.
• RAID 0 - Stripes the data at the block level to maximize performance, however that increases the risk of lost data versus individual disks.
• RAID 1 - Mirrors all data onto all of the drives contained in the array. This provides the highest level of protection, however it is also relatively inefficient.
• RAID 3 - Uses byte-level striping with a dedicated parity disc. This can provide similar performance to RAID 0 but can survive the failure of one drive.
• RAID 4 - Same as RAID 3, but uses block-level striping.
• RAID 5 - Uses block-level striping with a distributed parity disc. This can provide similar performance to RAID 0 but can survive the failure of one drive.
• RAID 6 - Uses block-level striping with two distributed parity discs. This can provide similar performance to RAID 0 but can survive the failure of up to two drives.
• RAID 10 - A combonation of RAID 0 and RAID 1. Data is striped across two RAID 1 arrays. This provides the performance advantages of RAID 0 and can survive at least one drive failure.
• RAID 0+1 - A combonation of RAID 0 and RAID 1. In this mode, two RAID 0 arrays are mirrored. This provides the performance advantages of RAID 0 and can survive at least one drive failure.
• Matrix RAID - A propreitary technology used by some Intel chipsets that allows drives to be partitioned and different RAID levels used on each block.