Level 3 combines data striping with a dedicated parity drive for error recovery. Level 5 stripes blocks of data and the parity checking formulas together across multiple drives, thus eliminating the need for a separate parity drive. Buy dual failover RAID controllers, redundant power supplies, cooling fans and host interfaces to ensure the best protection against catastrophic array failures. Equip your RAID array with an uninterruptible power supply. Investigate your RAID manufacturer's software as well as its hardware.
RAID levels have no hierarchy of value.
It is also dependable, but when a drive fails, recovery time is slow because the information on the failed drive must be reconstructed from the parity data on other drives. Not so common There are several other seldom-used RAID levels, including levels 4 and 6. J.B. Miles, of Pahoa, Hawaii, writes about communications and computers.