Thirty Years of RAID

Last year marked the 30th anniversary of RAID technology, which is still widely used by business and home users alike. How has a technology endured three whole decades, and how long will it be around for?

The term RAID was invented by David Patterson, Garth Gibson and Randy Katz in 1987. Originally referred to as a “Redundant Array of Inexpensive Disks”, they argued that an array of cheap hard disks developed for the home market (“non-mainframe computers”) could perform better than a top performing drive used for business data, which were known as “SLEDs” (Single Large Expensive Disk). Hard disk drives were expensive, so using as few as possible was a priority for businesses. Even though, as the trio pointed out, that multiple drives means a higher chance of failure, by configuring them for redundancy, the reliability of RAID could exceed that of SLED.

Put simply, the data in RAID systems is replicated across multiple hard disk drives. The drives are then configured so that data is either divided or replicated across two or more drives for increased performance, capacity, or data protection. There are three main techniques involved in RAID – mirroring, striping, parity and redundancy. Mirroring is where data is replicated across multiple disks, which is used in RAID 1, which offers the user double the read performance. Striping is the most basis RAID technique, also known as RAID 0. Simply put, data is striped or spread out across multiple hard drives, but if one drive fails, the whole system does. Parity describes a way of distributing data across a RAID system so it can be restored in the case of a failure, and redundancy is the duplication of critical components to act as a safety net.

RAID 5 is a common RAID configuration and offers the user a compromise between performance and reliability. For RAID 5, you need at least three drives, preferably more - we see RAID 5 arrays with five-plus hard drives. RAID 5 – like RAID 0 – stripes the user’s data across multiple drives, and offers a combination of increased speed and redundancy. The disadvantage, as with all RAID configurations, is that it isn’t a substitute for a logical backup – your data still isn’t 100% safe. No RAID configuration protects your data against malware, human error or natural disasters.

RAID is a cheap way for businesses and home users to store data with the perks – speed, reliability and capacity – that suit them. The chances are, even with the advent of solid state, flash-based storage, it won’t be going away any time soon.

RAID Data Recovery