Scream if you want to go faster! Speed packs that fun filled adrenalin rush, but inevitably adds that element of risk. RAID0 in no exception - you get the advantage of faster read and write access, but the increased possibility of complete hard drive wipeout. If you're a complete novice to PCs, read on and we'll take you on a whirl wind tour of all things RAID related.

Giving RAID it's complete title of Redundant Array of Independent Drives does little to help matters. So let's delve deeper and put this in terms we both understand. Let's say you were unloading a lorry with a team of people. The best way to organise things would be to create a chain so that each person walks a minimum amount to collect a parcel, and everyone is working at the same time. Now imagine you had two or more drives. Rather than simply use one disk to read or write a file, each drive could simultaneously write a piece of the file to its own disk. This is our RAID array, and in its simplest form, RAID0, two or more physical drives are combined to make one.

Taking this a step further, data is stored on the separate drives in "stripes" (you may have heard RAID0 referred to as "striping"). Each stripe is set at a certain size and where files are greater in size to this pre-defined stripe, the file is separated and saved in chunks on the separate drives. The advantage is obvious here: each disk is used to its full potential so that the transfer speed is multiplied by the number of drives in the array. If you had two drives with a maximum transfer rate of 20MB/s, the limit then becomes 40MB/s. As ever, there are limitations and the speed multiple is limited to the slowest drive in the system. The size of the array is also dependant on the smallest drive, so if you don't want to waste space, ensure you use identical drives!

RAID0 or "stripe sets" are ideal for video editing where file sizes are typically large and you gain from the increase data transfer rate - essentially your files are served up quicker as the possibility of a potential bottleneck is reduced. Both benchmarks and user experience suggests there's a real world efficiency gain to RAID0 in a video editing, with real time rendering of multiple tracks reportedly quicker. But there are disadvantages. As data is spread across two or more drives, a hard drive failure on just one drives in a RAID0 setup will result in the data corruption across all drives. A double whammy, resulting two times the data loss of an independent drive. This kind of set-up is not therefore fault tolerant, and in a video editing environment, where back-ups are essential, this may not be the ideal scenario.

But RAID isn't just about performance but also reliability. And we can take advantage of RAID1, or mirroring, when data integrity is more important than performance or maximising disk space. RAID1 creates an identical copy of your data on a separate disk, so that in the event of a failure there is an existing backup to which you can revert. Although performance of RAID1 is clearly less than RAID0, the read performance is marginally better than independent drives as data is read from the faster drive. Write performance is, however, slower than independent drives as the data must be compared across all drives after being written.

If you want the best of both worlds, RAID0 and RAID1 can be combined to create either RAID0+1 or RAID1+0. RAID0+1 is a mirror of stripes, so that when one drive fails in an array, it can be rebuilt from the other. This type of array cannot rebuild data from a failure on more than one sub array. RAID1+0 is a stripe of mirrors where a drive from each mirror could fail without causing data loss and is therefore more fault tolerant to multiple drive failures.. In each of these, you get the advantage of both fault tolerance and performance, but you need double the amount of drives for the same capacity as RAID0 (so this means at least 4 drives).

Although RAID0 and RAID1 are the most common flavours of RAID on desktop PCs, there exist a whole host of different kinds, each offering various ways of arranging data across multiple discs. RAID5 is the most commonly used variety is server environments, but we are starting to venture away from the desktop environment here.

How do I get RAID?

There's two ways of creating a RAID array, one software based and the other hardware based. Software based RAID arrays rely on the operating system to manage the disks and are generally slower than hardware based solutions where the drives are managed by dedicated controllers. The creation of a software based RAID under Windows is way beyond the scope of this article, but you can find more information at techimo hardware. This is perhaps a viable alternative to those that want to experiment without shelling out money!

The hardware based solution would most probably be the most appropriate to the less technical user. Most modern motherboards are fitted with a RAID controller as standard, but a controller can easily be fitted as a PCI expansion card. For detailed information on how to set-up a hardware RAID array, I recommend this guide