RAID stands for Redundant Array of Independent Disks, and combines multiple hard drives together in order to improve efficiency. Depending on how your RAID is configured, it can increase your computer’s speed while giving you a single drive with a huge capacity. RAIDs can also increase reliability. There are three main types of RAID that we're going to discuss – RAID 0, RAID 1 and RAID 5.
RAID 0 turns two or more hard disk drives into one bigger, faster storage unit; but it significantly increases the chance of a data disaster. When you save a file to a RAID 0, it is split into sections and distributed across the drives. The multiple drive heads working together means that the array can read and write data much faster than a single drive can. It massively increases the capacity, too – if you’ve got four 1TB drives, you effectively have a 4TB hard drive that’s super-fast. However, not only have you got a drive that is four times the size, it also has four times the risk of a crash. If one drive crashes, you lose everything.
RAID 1 – or disk mirroring – replicates your data to two or more disks, and is the perfect choice for users who need high levels of performance. Data can be read extremely fast because both disks are operational, but write operations are slower because each operation is done twice. But because the two drives mirror each other and contain the exact same data, if one fails, the other keeps working – meaning no lost data or downtime. But RAID 1 shouldn’t be used as a substitute for a real backup – the drives will still be susceptible to the usual things like physical damage. If your hard drive is ina fire or flood, for example, it will affect both of the drives.
RAID 5 offers the benefits of RAID 0 and RAID 1 – capacity, speed and protection. You will, however, need at least three drives (although most people use five), with all but one being used for storage. It is by far the most common configuration for business servers, and uses disk striping with parity. Data is striped across all of the disks in the RAID, along with parity information needed to rebuild data in the event of failure.
But while RAID offers clear advantages, there are some downsides. The main drawback of RAID 1 for example, is that for the required disk space, you need to double the capacity you have to purchase. So, for example, to store 1TB of data you will need a capacity of 2TB. With RAID 5, only four fifths of the capacity you purchase will be usable, as one of the disks acts as a parity disk, knowing where all the data is stored. RAID 5 volumes do also take a long time to rebuild, and you may have to consult an expert in RAID data recovery
