RAID Types for the A+ Certification Exams
RAID (Redundant Array of Inexpensive Disks) is a method of implementing redundancy (duplicated information) on your hard drives — if one disk fails, the other disk(s) can provide the missing information. There are many different levels of RAID, but the following are the only RAID levels pertinent to the A+ exams:
RAID 0: Disk striping (striped volume). With RAID level 0, the data is split across drives with no data redundancy. RAID level 0 improves read and write performance by writing to multiple drives at the same time. You need a minimum of two drives.
RAID 1: Disk mirroring/duplexing (mirrored volume). With disk mirroring, the data is written to both drives involved in the mirror to provide data redundancy. Windows 7 supports disk mirroring.
RAID 5: Disk striping with parity (RAID 5 volume). With RAID 5 volumes, the data is written to multiple drives along with parity information that is used to help recover data if a single drive fails. RAID 5 volumes need a minimum of three disks.
RAID 10: Mirrored disk striping. RAID level 10 is also known as RAID 1+0 because it is disk striping while mirroring the data written in the stripe.