Kbase P73264: What are the differences between the different levels of RAID
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
02/07/2008 |
|
Status: Unverified
GOAL:
What are the differences between the different levels of RAID
GOAL:
RAID Levels explained.
FIX:
RAID level 0
Data is striped over several drives, but there is no redundant drive, so this is not a true fault-tolerant configuration.
RAID level 1
This is a mirroring solution. Data is written in blocks to two separate drives simultaneously.
RAID level 2
This level provides data striping at the bit level over all drives in the array. Additional drives are used to store Hamming codes. Error-correction algorithm reconstructs data from the codes, so mirrored drives are not necessary.
RAID level 3
Data is striped to multiple disks in blocks, and parity information is generated and written to a single parity disk. The information on the parity disk can be used to reconstruct data.
RAID level 4
This level is similar to RAID level 3, except that data is striped in disk sector units rather than as bits or bytes. Parity information is also generated.
RAID level 5
Data is written in disk sector units to all drives in the drive array. Error-correction codes are also written to all drives. This level provides quicker writes because the parity information is spread over all the drives, rather than being written to a single parity drive.
RAID level 6
Similar to RAID level 5, but with added fault tolerance. A second set of parity information is written across all the drives. This is equivalent to double mirroring. This level may be more fault tolerant than necessary and has poor performance.
RAID level 10
This is basically RAID level 1+0, where striping is applied across multiple RAID 1 pairs.
RAID level 15
This is RAID level 1+5, where two complete RAID 5 systems are mirrored for added fault tolerance.
See Solution, P66330, Does the Progress RDBMS work with RAID.