While the term RAID (redundant array of inexpensive disks or redundant array of independent disks) was first coined in 1987, the technologies comprising the original five levels of RAID were used in the years prior. The exact features and functionality of RAID have evolved over the years, and, due to the increasing affordability and accessibility of technology in general, RAID is becoming more popular amongst professionals and personal users alike.
Implementing RAID on Your Computer
Although it's not recommended for beginners, the process of installing and implementing RAID on a computer is a rather straightforward process. Start by procuring the necessary hardware:
- RAID controller: While many motherboards come equipped with an integrated RAID controller, some do not. If your computer doesn't, you'll need to purchase either a RAID controller or a RAID adapter card.
- Multiple hard drives: RAID works by utilizing two or more hard drives to achieve a greater level of data redundancy and protection, so you'll need multiple hard drives to implement RAID.
- Hand tools: A small screwdriver will be necessary to insert and remove the necessary screws during installation.
The actual installation process varies, depending on whether or not you're using a RAID controller or a RAID adapter. Once installed, you can begin to configure the RAID system to meet your needs.
Standard RAID Levels
While there were originally five different levels of RAID implementation, these levels have evolved to include nested levels in some cases. There are also numerous non-standard RAID levels, many of which are proprietary.
In modern computing, the standard RAID levels include:
- RAID 0: This level includes data striping but lacks data mirroring or parity. Since the data contained within each file is striped across multiple drives, a failure on any one drive in the array will result in losing all of your files.
- RAID 1: This level uses data mirroring exclusively, which writes data to two or more drives. If one drive fails, your data is still accessible through another, functional drive.
- RAID 2: Combining data striping with parity, RAID 2 is mainly a historical artifact in modern computing.
- RAID 3: Byte-level data striping and a dedicated parity drive is used in this level, but RAID 3 isn't commonly seen in modern computing.
- RAID 4: This level includes block-level data striping and a dedicated parity drive, although it's considered outdated in lieu of the proprietary RAID-DP.
- RAID 5: This level uses block-level data striping and a distributed parity. At least three separate drives are required, and the process of rebuilding an array requires data to be read from every device. Not only is this is a long and monotonous process, but it sets the array up for additional drive failures.
- RAID 6: Block-level data striping and a double distributed parity is used, primarily in large-scale RAID systems, to achieve RAID 6.
As mentioned, there are additional RAID levels, too. Numerous non-standard levels exist, all of which are used in highly specialized cases, and some organizations have developed their own, proprietary RAID implementations to meet their unique needs.
You may read more about RAIDs in the article in Wikipedia: RAID.