(not used in practice) - data is split at bit level at written to multiple drives.

Redundant Array of Inexpensive Disks – parallel array with ECC. Level 2 introduces hamming code error checking across the disks. This introduces the possibility of data recovery without a complete duplication of data, although it does require several check disks. This also requires that all disks in a group be accessed, even for small transfers, and the process has to wait for the slowest to finish before the transfer is complete. See also RAID.

Error correction data written to separate disk.