With the constant increase of the available bandwidth for consumer broadband Internet connections, people are starting to download more and more stuff (music/videos but also pictures, software, e-books, ...). Furthermore, digital cameras or digital camcorders are starting to be quite cheap. With all these new electronic toys, we need more and more storage available. Hard disk drives are available up to 500 GB, but that's for an high-end drive, and what happens if the drive fails ? You loose 500 GB of data, personnal photos, and so on. Not funny.
Commonly used in servers, RAID arrays offer an elegant solution to prevent loosing data in case of a hard drive failure while giving a lot of storage space. A RAID setup consists of a RAID controller, connected to several hard drives (from 2 to many). The RAID controller can then use the hard disk drives in different ways, according to what the system administrator decided, each way corresponding to a certain level of security and available space. Typically, the more security you have, the less space you have, because fault tolerance is achieved by storing special data in one or more hard drives, thus these hard drives can no longer be used to store real data. For more information about how RAID works, check out this page at the Advanced Computer & Network Corporation website.
For example, in a RAID 5 array, you have N+1 drives of equal C capacity. These N+1 harddrives will be seen by your computer as a single drive, of capacity N*C. There is some capacity that is lost because of the parity system that allows to find the data even if a single hard drive is faultly. RAID 5 offer a good security level at a very moderate cost. The problem is that RAID controllers are typically expensive, and it's the same for the physical arrays used to store the hard drives.
A wise guy at Inventgeek.com took a metal case, some cheap SCSI drives bought on eBay for a few dollars each, and a SCSI RAID controller also bought for a few bucks. He then simply screwed the drives in the case, and powered them with a big fat power supply unit. Simple ? Yes, for sure. But it's usually the simplest ideas that are the hardest to find, especially when they are elegant. Undoubtly, this one is.
Check out the project description !
Thanks to the Inventgeek.com team for allowing me to put the picture of the RAID array in this post.