What is RAID Storage and What is the Best RAID Configuration?

What is RAID Storage and What is the Best RAID Configuration?

2019-04-17T18:34:45-05:0015 Apr 2019|

What is RAID?

RAID or Redundant Array of Independent Disks, is a way to combine multiple smaller disks into a single, more capable, storage device. The disks are arranged in a variety of configurations, known as RAID levels, each with its own advantages and disadvantages. A simple RAID can be started with just two drives, while more complex configurations can contain a theoretically unlimited number of drives.

RAID isn’t always hardware, it can also be implemented using software. Hardware tends to be found more often in Windows systems, while software implementations are more common in modern enterprise systems or open source servers.

Why should I use a RAID?

The RAID advantages are numerous but depend on your intended configuration. In general, RAID helps with:

  1. Increased fault tolerance or ability to function after one or several disk failures.
  2. Faster read and write speeds.
  3. Larger capacity to hold all your data.

In conclusion, organizing your system this way can help to combat failed hard drives or data losses, increase performance and increase capacity.

Basics of RAID Configurations

There are three main functions of RAID storage. They are the reason RAID configurations can be useful for anyone storing and accessing large quantities of data.

  • Striping – splitting the flow of data between the drives.
  • Mirroring – storing identical copies of data simultaneously, in different blocks.
  • Parity – in the case of a failed drive or missing data, this function helps calculate the missing block to prevent the system from going down.

What is RAID 0?

RAID 0 Diagram

RAID 0 splits data across two or more disks, with no parity, redundancy or fault tolerance. This means, if one of the drives fails, the whole system will be unable to function. While it offers none of those capabilities, it does offer very fast read and write speeds.

What is RAID 1? Is it the same as mirroring?

RAID 1 Diagram

RAID 1 is also known as mirroring. This method involves writing the same data on two different drives. This is not a setup for increasing speed, but simply for reliability. RAID 1 is a great option because it has good fault tolerance and only requires two drives.

Why is RAID 5 the most popular option?

RAID 5 Diagram

RAID 5 is currently the most common and widely accepted as one of the more secure configurations. It requires at least three drives and can recalculate the data of one of the other data blocks, should those data blocks no longer be available. That means a RAID 5 array can withstand a single drive failure without losing data or access to data.

RAID 5 vs. RAID 6 – Is RAID 6 the Best Option?

Nearly identical in setup to RAID 5, but RAID 6 uses one more parity block so you can have two disks fail and still have an operational system.

RAID 6 is typically going to be the best option for a RAID storage solution because of its ability to utilize two different parity functions, making it capable of repairing multiple lost drives without data loss.

This configuration has an essentially identical read performance as RAID 5 but suffers a little in write performance depending on how the system is set up. Both options reduce the likelihood of data loss, and your need for a RAID recovery service, if maintained correctly.

Less Common RAID Configurations

Raid 0+1 (10)

This method involves both striping and mirroring. Using these methods together help the RAID improve performance and fault tolerance.

RAID 2

Rarely used, this method stripes data at the bit rather than block level and uses a Hamming code for error correction.

RAID 3

Also rarely used, RAID 3 uses byte-level striping with a dedicated parity disk. This setup is unable to service multiple requests at the same time.

RAID 4

This configuration consists of block-level striping and a dedicated parity disk. This allows the system quick read speed, but generally, slower write speed.

RAID 5E

This is a layout variation of RAID 5 in which a designated spare space allows rebuilding a failed array right away. This space is always left empty in the case of a failure.

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