1. RAID 3:
RAID 3 consists of Byte-level Striping. It stripes the data onto multiple disk. The parity bit generated for each disk section and stored on a different dedicated disk. This level overcome the single disk failure.
- Data can be transferred in bulk
- Data can be accessed in parallel.
- It require an additional drive for parity.
- In case of small size files it performs slowly.
2. RAID 4:
RAID 4 consist of Block-level Striping. In this level entire set or block of data written onto the data disk and then the parity is generated and stored on a different set of disk. This level overcome at most one disk failure. If more than one disk failure occur then there is no way to recover the data. Both RAID 3 and RAID 4 require at least three disk to implement RAID.
- It facilitates simultaneous I/O request because of Block striping.
- Storage overhead is low.
- Parity disk may lead to bottleneck.
- Slow random writes because of separate block parity.
Difference between RAID 3 and RAID 4 :
|SR.No.||RAID 3||RAID 4|
|1.||RAID 3 stands for Redundant Array of Independent Disk level 3.||RAID 4 stands for Redundant Array of Independent Disk level 4.|
|2.||In RAID 3 technology, Byte-level Striping is used.||In RAID 4 technology, Block-level Striping is used.|
|3.||In this level, parity bits are generated for each disk section and stored on a different disk.||In this level, parity bits are generated for the entire block of data and stored on a different disk|
|4.||Random read will have worst performance.||Good Random reads, as the data blocks are striped.|
|5.||Performance is good in case of large sized files.||Performance is low because only one block is accessed at a time|