What is a RAID

For the first time, the word RAID appears in 1987, in a Berkeley University article.

RAID stands for "Redundant Array of Independent Disks".

Creating a RAID system allows to reach the following goals :

• Creating more storage volume by assembling some HDDs together.
• Depending the type of RAID, it will create a secure volume.
• Also depending the type of RAID, it will create a fast access storage.

There's 2 main types of RAID systems :

• RAID systems with one or more redundant HDD(s). They can keep on working with X HDD failure(s). X is equal to the number of redundant HDDs.
• RAID systems without redundant HDD. These ones won't tolerate any HDD failure.

So, there's secure RAID systems, such as RAID 1, RAID 5 and RAID 6. And insecure RAID systems such as JBOD and RAID 0. There can be also combined RAID systems that are a concatenation of 2 different types of RAID, such as RAID 1+0, RAID 0+1 or RAID 0+5.

The RAID parameters can be managed either with a software installed on the OS (Windows, Linux, Mac OS), or with a hardware component, such as the motherboard or even better, a dedicated RAID controller.