Level 3 is typically implemented at the BYTE level. These Levels combine the performance of RAID 0 with a redundancy feature. If a drive fails, the data can be restructured by the parity drive. RAID 3 and 4 are best suited for large transfer sizes and rates where redundancy is important. The parity information is calculated during write time and can effect overall performance.
Spare drives take over in the event of a drive failure.
RAID Level 5 stripes data and parity information at the block level across all the drives in the array. Parity is written onto the next available drive rather than a dedicated parity drive. Reads and writes may be performed concurrently. This algorithm is best suited for smaller data transfers. Spare drives take over in the event of a drive failure.