A RAID level that uses a technique similar to striping, but on the bit level. (Data is split at the bit level and distributed across the disks in the RAID for storage.) An error correction code, called a “Hamming code,” is calculated and written to a dedicated disk at the same time the data is stored. When the data is read back into the computer, the Hamming code is also read to ensure that no errors occurred. Due to its complexity, substandard performance due to bit-level operation, the cost of extra disks, and the need for a specialized hardware controller, RAID 2 never really caught on for popular usage.