Gillware Inc.

Single level 2 RAID systems are very rare. RAID 2 stripes data across many disks at the bit level and calculates redundancy bits that get stored on dedicated disks. The data on the redundancy disks is calculated using Hamming Error Correction Code (ECC). When data is read, the ECC is also read and the system is able to correct for errors that occurred in writing. RAID 2 is not used in practice today since modern drives have ECC codes built in to each sector on the disk.

Single level RAID 3 is similar to RAID 5 in that it stripes data across many disks and calculates parity. But instead of distributing parity across many disks, RAID 3 uses a dedicated parity disk. RAID 3 also stripes data on the byte level.

Single level RAID 4 is similar to RAID 5 in that it stripes data across many disks and calculates parity. But instead of distributing parity across many disks, RAID 4 uses a dedicated parity disk. RAID 4 differs from RAID 3 in that it stripes data on the block level.

Single level RAID 6 is similar to RAID 5 in that it stripes data across many disks and distributes parity through out the disks. But instead of storing one set of parity data per block, RAID 6 stores two sets of parity data per block. As a result of this additional parity, RAID 6 requires a minimum of four disks to implement compared to three for RAID 5. This "dual distributed parity" allows for simultaneous loss of two drives in the system.

Gillware looks forward to helping you with your RAID array reconstruction needs. To place an order please call our 800 number.