What does RAID mean?

RAID has been around since the late 80s, and chances are if you've spent time around a PC you've heard the acronym spoken aloud. So what does RAID mean, and why does it matter to you?

What is RAID?

What is RAID?

The Redundant Array of Independent/inexpensive Disks (RAID) was created in 1988 in order to deal with costs of high-performing disk drives. The inventors argued that an array of inexpensive disks could outperform a single expensive disk. Several iterations of RAID have since been created (and in some cases mostly abandoned), each tackling a certain set of problems.


The first RAID version created, RAID 0 is intended to provide users with fast read and write speeds and thus fast performance. Despite its name there is no data redundancy — data is striped across drives, meaning each drive holds a piece of the overall information. Striping means quicker data access, but if one drive fails they will all fail, resulting in a complete loss of data. Speeds are measured by the number of drives in the array, so consider an array with four drives to be four times faster than a single drive — it can read from four different spots at a time, after all. RAID 0 setups are favorites among computer gamers where performance trumps fault tolerance.


A RAID 1 setup consists of at least two drives that are mirrored to contain the exact same information. This RAID setup contains fault tolerance, as one drive going down will not result in the other drives going down as well. As long as one drive works the array will continue to operate, making this a favorite of those who require high reliability.

There is, however, a blow to write performance and storage capacity. When data is written to the array it must be written to each drive independently, meaning write speeds are based on the slowest drive-speed of the group. Likewise, storage capacity is dependent on the size of the smallest disk — you can't store more data on a single drive than you can on any other.

RAID 1 is the expensive choice since its efficiency can basically be described as the number of drives divided by its own number. For example, if you have two drives (the minimum number for a RAID 1 setup), you're only getting the storage space of one drive since the other is a backup. This equation is the same no matter how many drives you have — a ten drive setup will still only have one drive's worth of information stored within (but some pretty impressive redundancy).


RAID 5 is the most popular setup due to its striping capabilities (very fast read and write speeds!) as well as a parity function that is distributed across drives. In the event of a drive failure an Exclusive Or (XOR) logic gate is used to piece together the lost drive using parity information on the other drives. This can be accomplished even while the other drives continue their regular function; you will not experience any down time if you lose a drive. For this reason a RAID 5 setup requires at least three drives.

A RAID 5 setup with three drives will still essentially lose 33% of its space for parity, but is still more cost efficient than a RAID 1 setup. It can also, as mentioned, repair a drive that was lost without experiencing any downtime. A RAID 5 setup with four drives is a favorite of many private users, as you only lose 25% of storage to data redundancy.

Is RAID right for you?

No doubt memories of 10MB hard drives costing thousands of dollars are still fresh in some of your minds. RAID was originally invented to cut the costs of 80s storage prices while simultaneously accounting for the high fail-rates of some early technology. RAID setups are still primarily used in large servers — think of corporations that require 24/7 access to their critical data.

Now, though, with storage on the cheap, RAID setups are used privately in conjunction with specialized tasks, and to avoid monthly fees and privacy concerns when dealing with cloud storage services.

What tasks require RAID setups, you ask? Many users of computer-aided design (CAD) and multimedia editors take advantage of the fast transfer rates and high fault tolerance found with RAID. There is nothing worse than watching your project disappear as your lone drive goes down without any backups. Computer gamers also love RAID setups, as they provide faster performance in an arena where milliseconds count.

Some people have taken a stand against cloud services due to privacy concerns, security risks, and high costs. Network-attached storage (NAS) is basically a computer managed by RAID that handles data from other computers on the network. You can buy pre-made NAS devices to which you simply add hard drives — we recommend QNAP or Synology.

RAID NAS setups available for purchase

As mentioned, RAID 5 setups with four drives are a bit of a sweet spot. You lose only 25% of storage space, and in the event of a drive failure you won't experience any downtime.



The QNAP four-bay NAS has 4GB of RAM and holds up to four drives. Users say it is great for streaming 4K video — it is quiet and can wirelessly transfer about 50mb per second.

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Synology Disk Station 4-Bay Network Attached Storage

Synology 4-Bay

The Synology four-bay NAS holds up four drives totaling 24TB of space and has a 1.6GHz Dual Core CPU. Users claim its built-in operating system is simple to use and has provisions for several uses, including security camera storage and mail server support.

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Both companies provide expandable RAID variants that let you extend existing RAID volumes. Check out more information on NAS setups and if they're right for you.

What is your RAID setup?

Let us know in the comments section below what badass setup you have running!

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