RAID

A couple of sharp guys in Berkeley back in the 1980s organized the many techniques for using multiple drives for data protection and increasing speeds as the redundant array of independent (or inexpensive) disks (RAID). They outlined seven levels of RAID, numbered 0 through 6.

       An array in the context of RAID refers to a collection of two or more hard drives.

RAID 0-disk striping disk striping requires at least two drives. It does not provide redundancy to data. If anyone drive fails, all data is lost.

RAID 1- disk mirroring/duplexing RAID 1 array require at least two hard drives. Although they also work with any even number of drives. RAID 1 is the ultimate in safety, but you lose storage space because the data is duplicated; you need two 100-GB drives to store 100GB of data.

RAID 2- disk striping with multiple parity drives RAID 2 was a weird RAID idea that never saw practical use. Unused, ignore it.

RAID 3 and 4-disk striping with dedicated parity RAID 3 and 4 combined dedicated data drives with dedicated parity drives. The differences between the two are trivial. Unlike RAID 2, these versions did see some use in the real world but were quickly replaced by RAID 5

RAID 5 –distributed parity instead of dedicated data and parity drives, RAID 5 distributed data parity information evenly acro