What is RAID?

RAID stands for Redundant Array of Independent Disks. A RAID uses two or more hard disk drives enclosed in an external storage solution. For the more techie folks, you can also build a RAID array inside of your computer. However, the latter requires a bit more work so, for the purpose of this article, we'll focus on simple, plug and play external storage RAID.


Here are the most commonly used RAID levels:

• RAID 0: Also known as "striping," RAID 0 provides full capacity with the fastest possible sustained throughput – continuous large sequential read/writes. RAID 0 takes a file and spreads it across two or more drives to reduce the time it takes to write or read the file. RAID 0 pays off in situations where speed is paramount, such as working with multiple streams of digital video.
• RAID 1: When you invest countless hours and dollars amassing hundreds of gigabytes of data, you would probably care more about data protection than speed. The easiest way to protect your data against accidental loss is to "mirror" the files. This can be achieved easily with a two-drive external storage solution. Whatever gets written to the first drive is automatically copied, or mirrored, to the second drive. This means if anything should happen to either disk, your data is still safe.
• RAID 0+1: RAID 0+1 Arrays require disks in multiples of four and is composied of a mirror of striped sets. It provides good speeds because of the RAID 0 striping, but cuts the available capacity of a device in half.
• RAID 5: Combines RAID 0 striping with data redundancy in an array with three or more disks. RAID 5 combines data safety with efficient use of isk space. Disk failure does not result in a service interruption because the data is read from "parity blocks." RAID 5 is useful for storage and for people who need performance and constant access to their data.
• RAID 10: Sometimes called RAID 1+0, it’s similar to a RAID 0+1 but reversed since RAID 10 is a stripe of mirrors. The data is striped, with each stripe appearing on two disks. One disk from each mirror pair can fail without losing your data. However, the remaining disk in the array becomes a weak point and (if it also fails) you lose data. RAID 10 arrays have disks in multiples of four. It provides good speed because of the striping, but the available capacity is cut in half.
• Concatenation: JBOD - "Just a Bunch of Disks." Each disk in the array is, well, a separate disk: there is no striping or mirroring. It's an easy way to add a large amount of storage capacity.

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