RAID 6 is a new level of RAID that was not originally envisioned by the inventor of the technology. Rather it is a new form of array that was conceived after extended time and development with other RAID arrays, most notably RAID 5. In fact, RAID 5 is the bedrock upon which RAID 6 is used.
As you may expect, much like RAID 5, RAID 6 is a kind of Redundant Array of Inexpensive Disks in which a computer uses block-level striping. Data is written in blocks on each of the drives on the array. In essence, it leaves parity data across all of the disks, allowing it to rebuild missing sectors of a file.
RAID 6 is similar in design to RAID 5 but with an additional parity block in which files are striped across disks. RAID 6 is designed to operate under optimal conditions with larger amounts of drives, as it is relatively space inefficient when used in small numbers. RAID 6 is contingent on mathematical computations known as syndromes in order to operate at full efficiency. It is because of these highly important computations that you acquire a card or controller which is expressly rated for RAID 6. This controller does not have to spend time, and lag performance, simply to operate as intended.
The Importance of Implementing the Correct Controller
RAID 6 is controlled by a typical RAID controller in either a software or hardware format, but it requires more precise computing in order to effectively manage the data. With additional calculations called syndromes, RAID 6 can then be configured to run on any number of disks, and provide as much data redundancy as conceivably needed with only additional calculations. These calculations can easily be managed by any specific RAID 5 or 6 controller.
The second layer of parity distribution provides a high level of reliability and more easily recreates files lost after a disk failure when compared to other forms of RAID. The additional data layer of RAID 6 protects against data failure by keeping enough parity bytes on-hand to reconstruct more than one drive, which hedges bets against the dreaded double hard disk failure. This type of failure can wipe out any other RAID arrays effectiveness almost immediately.
Not as User-friendly
This ability to rewrite and rebuild bad data sectors in the presence of two failed hard disks is what makes RAID 6 such an attractive option for both personal and business end users alike. The number of disks involved usually restricts RAID 6 to computing experts or business users, but it is certainly a viable and reliable form of RAID for anyone who has the money to finance such an operation.
The reliability of RAID 6 is what makes it a penultimate form of backup for those who find data integrity to be their chief concern above all. Capacity or storage limits are not as robust as they are with forms of RAID which provide no kind of data redundancy, but you would be hard-pressed to find another RAID array that can protect against catastrophic loss of data nearly as well.