RAID stands for Redundant Array of Inexpensive Disks. RAID comes in several different forms, however below we have described the most common types of RAID. It’s recommended in any form of RAID to use identical specification drives for the best compatibility and performance.

RAID 0 (Striping)

RAID 0 requires two physical hard drives. RAID 0 operates by essentially splitting your data across two drives instead of one, meaning superior performance than just one standard hard disk. For example, if you bought two 300GB hard drives and configured them in RAID 0, 600GB (visible as one drive under Windows) would be useable. RAID 0 although fast does have one major disadvantage. If either hard drive fails, all your data will be permanently lost!

RAID 1 (Mirroring)

RAID 1 requires two physical hard drives to operate. As the name Mirroring suggests, when saving a document to your local disk, a copy of your file is made to both hard disks. Unlike RAID 0, if one of your hard drives breaks, it’s simply a case of replacing the faulty drive. The existing hard drive will then re-copy all its information to the new hard disk restoring the redundancy. RAID 1’s disadvantage is cost. The user only gets half of the total capacity. For example, even though you bought two 300GB hard disks (which totals 600GB), only 300GB would be available/useable under Windows.

RAID 3

RAID 3 requires three physical hard drives to operate. Data is subdivided (striped) over two or more drives working in parallel, with a third hard drive storing parity information. What’s parity information I hear you ask? Parity is used to calculate data in two drives and store the data on the third (a dedicated parity drive). The theory is, that if one drive fails, data can be re-built from the existing two drives. RAID 3’s advantages are that it offers speed and redundancy.

RAID 5

RAID 5 without a doubt is the most common and most secure form of RAID used in high end workstations and servers. Similar to RAID 3 it requires a minimum of three hard drives, but unlike RAID 3, RAID 5 doesn’t operate in parallel, but rather independent read and write operations. RAID 5, unlike RAID 3 doesn’t have a dedicated parity disk, but the parity is also divided across the hard drives. RAID 5’s advantages are that read operations are very fast and it offers excellent redundancy.

RAID 01 and RAID 10

Both RAID 01 and RAID 10 require four physical hard drives to operate, but although similar in name, they are not one and the same! In both instances, unlike RAID 5, RAID 01 and RAID 10 offer mirror and striping, but without parity. RAID 01 is a mirror (a copy) of two striped sets, whereas RAID 10 is a stripe (a divide) across a number of mirrored sets.