In some circles, RAID stands for Redundant Array of Independent Disks, referring to the fact that, if one drive in a RAID array fails, providing the array uses mirroring rather than data striping, it can be pulled out and replaced without affecting the entire array. In other words, the disks operate independently.
But when RAID arrays first came into being, the acronym stood for Redundant Array of Inexpensive Disks. Using multiple smaller hard drives was (and is) much cheaper than using one larger hard drive or server for data storage.
Due to advances in technology and changes in the data storage industry -- namely, consolidation and cheap competition amongst the top companies -- hard disk drive prices continue dropping.
Affordable RAID 5 Solutions
There is really no reason not to employ a RAID 5 array or greater, which uses both mirroring and striping techniques for faster performance and greater stability.
If two or more hard disks in a RAID 5 array fail, you may still need professional data recovery services, but the more hard drives you use in the array, the less the chances of catastrophic system failure and the loss of data.
RAID, RAID Everywhere
With major manufacturers like Samsung, Seagate and others producing hard drives of 3 and 4 TB at reasonable prices, you might wonder why you need a RAID array for increased storage capacity.
The benefits in performance speeds and stability with a RAID 5 array make it well worth the cost.
Unless two or more drives fail in a RAID 5 array, your data will be preserved. And you can always perform a “hot swap” http://www.24hourdata.com/blog/does-your-raid-server-have-hot-standby on a single failed hard drive.
Today, RAID 5 arrays are affordable enough to use in small business and home server environments, as well as corporate data base applications.