The basic idea behind RAID is to combine multiple small,
inexpensive disk drives into an array to accomplish performance
or redundancy goals not attainable with one large and expensive
drive. This array of drives appears to the computer as a single
logical storage unit or drive.
RAID allows information to access several disks. RAID uses
techniques such as disk striping (RAID
Level 0), disk mirroring (RAID Level 1),
and disk striping with parity (RAID Level
5) to achieve redundancy, lower latency, increased bandwidth,
and maximized ability to recover from hard disk crashes.
RAID consistently distributes data across each drive in the
array. RAID then breaks down the data into consistently-sized
chunks (commonly 32K or 64k, although other values are
acceptable). Each chunk is then written to a hard drive in the
RAID array according to the RAID level employed. When the data
is read, the process is reversed, giving the illusion that the
multiple drives in the array are actually one large drive.
