What is RAID in Linux?

What is RAID? and Levels of RAID in Linux?

RAID (originally Redundant Array of Inexpensive Disks) now a commonly Redundant Array of Independent Disks is a data storage virtualization technology that combines multiple disk drive components into a logical unit for the purposes of data redundancy or performance improvement.

On most situations, you will be using one of the following four levels of RAIDs.

  1. Level 0 – striped disk array without fault tolerance
  2. Level 1 – mirroring and duplexing
  3. Level 2 – error-correcting coding
  4. Level 3 – bit-interleaved parity
  5. Level 4 – dedicated parity drive
  6. Level 5 – block interleaved distributed parity
  7. Level 6 – independent data disks with double parity
  8. Level 10 – a stripe of mirrors.

This article explains the main difference between these raid levels along with an easy to understand the diagram. In all the diagrams mentioned below:

A, B, C, D, E, and F – represents blocks

p1, p2, and p3 – represents parity

RAID Level 0

Following are the key points to remember for RAID level 0.

  • Minimum 2 disks.
  • Excellent performance ( as blocks are striped ).
  • No redundancy ( no mirror, no parity ).
  • Don’t use this for any critical system.

RAID LEVEL -1

Following are the key points to remember for RAID level 1.

  • Minimum 2 disks.
  • Good performance ( no striping. no parity ).
  • Excellent redundancy ( as blocks are mirrored ).

RAID LEVEL 5

Following are the key points to remember for RAID level 5.

Minimum 3 disks.

Good performance (as blocks are striped ).

Good redundancy (distributed parity).

Best cost-effective option providing both performance and redundancy. Use this for DB that is heavily read oriented. Write operations will be slow.

RAID LEVEL 10

 

Following are the key points to remember for RAID level 10

  • Minimum 4 disks.
  • This is also called as “stripe of mirrors”
  • Excellent redundancy ( as blocks are mirrored )
  • Excellent performance ( as blocks are striped )
  • If you can afford the dollar, this is the BEST option for any mission-critical applications (especially databases).

In most critical production servers, you will be using either RAID 5 or RAID 10.

How to Implement the RAID

Implementing the RAID will be two types

1. Software RAID and

2. Hardware RAID

 

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