RAID in computers is an acronym for Redundant Array of Independent Disks. While its name suggests that RAID is designed specifically for creating a redundant disk array, this isn’t necessarily true as RAID is simply a method of using multiple storage drives together rather than individually, or in a JBOD (Just a Bunch of Disks) configuration. When several drives are used in a RAID configuration, the resulting array will appear as if there’s only a single drive attached in the Operating System.
RAID arrays have several different modes, or levels, which determine how the disks will work together. While some RAID levels will stripe data for better performance, other RAID levels will mirror data for better redundancy. Some of the most common RAID levels include:
- RAID 0: This RAID level is the most dangerous of the bunch, but will provide the greatest performance and capacity. Unlike other RAID levels, RAID 0 stripes data across multiple drives to increase performance beyond the capabilities of a single drive on its own, but offers no data redundancy in the process. As a result, even the failure of a single drive can cause complete data loss.
- RAID 1: This RAID level is the safest and most secure however, comes at a cost of performance and capacity. In this RAID 1, data is mirrored across two drives so that if one drive were to fail, the second could take its place until a new drive is installed and the RAID array is re-built.
- RAID 5: This RAID level attempts to be a middle ground between RAID 0 and RAID 1. Rather than wasting a full drive mirroring a complete copy of the data on another drive, RAID 5 requires a minimum of three drives and uses at least one of the drives as a parity drive for storing parity data. In the event of a drive failure, the parity drive along with another drive is able to re-build the data on the failed drive.
- RAID 10: This RAID level combines RAID 1 and RAID 0 quite literally by not only striping data across drives, but also mirrors them as well.