RAID 2 (redundancy through Hamming code)
Works on a word basis + Hamming code
Splitting each byte into a pair of 4-bit nibbles
Adding 3 parity bits
7 bits are spread over the 7 drives
Performance is good
In one sector time, it could write 4 sectors
Losing one drive do not cause any problem
All the drives must be synchronized
On a single write, all data disks and parity disks must be accessed