ABSTRACT
Data storage protection is designed to act as the first line of defense against individual hard drive failure. In addition to the potential for higher reliability, redundant arrays of inexpensive disks (RAID) was also developed as a mechanism to offer improved storage performance, particularly compared to monolithic disks developed for mainframe computers at the time. There are a number of different RAID levels. RAID-0 offers no protection. RAID-1, otherwise known as mirroring, is where two hard drives are kept 100" in sync with one another. RAID-5 attempts to balance data protection with provided capacity by using the notion of parity. RAID-4 is similar to the behavior of RAID-5, except that the parity disk is dedicated that is, parity is not striped across all drives in the system. RAID-6 extends the basic principle of RAID-5 by adding a second parity stripe. Nested RAID refers to two RAID levels combined for greater performance, storage efficiency, or protection.
