What is RAID (Storage)

RAID stands for “Redundant Array of Independent Disks”. In some cases, it is used to refer to “Redundant Array of Inexpensive Disks,”

RAID was developed to bring together multiple, cheaper drives into one fast drive with a higher capacity. It was also designed to enable redundancy such that if a drive crashes, the array plus the data stay intact. The terms, one-disk or two-disk are commonly used to refer to the quantity of drives that may crash as the array stays viable

For small enterprises, redundancy is critical because drives do fail. However, data redundancy in RAID does not shield against data loss due to natural disaster, theft or malware. It is not a substitute for good data backup practices, though it guards against drive failure.

Levels of RAID

  • There are varying levels in which drives are organized in RAID
  • These levels are commonly referred to in terms of numbers. Most small office and consumer markets opt for RAID 1, RAID 5 and RAID 0.
  • There are many higher options that include levels such as 10, 5+1, 6 and JBOD which means ‘Just a Bunch of Disks’
  • Other methods include the Virtual Disk by Microsoft and abstract RAID options like Netgear X-RAID, Drobo BeyondRAID, and Synology SHR.

Functionality of Different RAID Levels

1. RAID 0

This works by distributing data over several drives increasing a drive’s speed of writing and reading. It is commonly used in other RAID levels. RAID 0 does not protect the drive from failure because no parity or duplicate information is written. In the case of drive crashe, the user is left with partial information.

2. RAID 1

This works by reading and writing similar data on drives that are in pairs, a process commonly called mirroring. The drives serve as equal partners making it possible to alternate in the event that one fails. Though it consumes a drive’s space capacity, RAID is the easiest way to generate failover storage for disks.

3. RAID 5

This approach provides data and speed redundancy. It reads and writes parity data from different disks then distributes it across all disks within the array. Parity data comprises tiny quantities of data that is mathematically derived from a bigger set that may accurately define the larger data quantity hence restoring it. It uses about a third of all disk space available and needs at least three disks to function.


This is not actual RAID but an option available on multiple disk storage that provides RAID. This method does not provide increased speeds or redundancy but concatenates a bunch of disks into one volume. Data is then written on the drive on till it gets full then it moves to the next till all drives are full. Though there are numerous network storage devices with this option, it is not recommended because it does not provide opportunities for using RAID 0.

5. Drive Extender

This option utilizes copying method allowing users to configure data that they wish to replicate based on folders.