RAID 2 is another RAID standard level configuration that provides very high data transfer rates. In RAID 2, a central controller synchronizes the disks by making them spin at the same angular orientation so that they all reach the index simultaneously. RAID 2 uses bit-level striping and each sequential bit is placed on a different hard drive. The error correcting code (ECC) used is the Hamming code parity, which is calculated across bits and stored separately in at least a single drive.
RAID 2 is one of at least nine types of RAID.
Techopedia explains RAID 2
RAID 2 differs from other levels of RAID because it does not use the standard way of mirroring, striping or parity. It implements these methods by separating data in the bit level and then saving the bits over a number of different data disks and redundancy disks. Hamming code is used to compute for the parity of the redundant bits to check and correct errors.
This configuration requires special driver hardware to make the disks spin synchronously. The r
RAID 2 controller was expensive and hard to implement. As a result, it never really caught on and was almost never used. Most of what RAID 2 offers is now is available in modern hard disks as a standard like ECC, so there's no reason to use it. Other RAID levels provide protection beyond ECC.