RAID

In this video from ITFreeTraining I will be looking at RAID. RAID allows multiple storage devices to be combined together to increase performance, add redundancy or both. In your IT career you will more than likely come across RAID, particularly when working with servers, so it is important to understand how it works.

RAID
RAID stands for Redundant Array of Inexpensive Disks. Originally it was designed for hard disks, but nowadays can used for other devices such as Solid-State Drives. For this reason, you may also hear it referred to as devices.

In some cases, you may also hear it referred to as Redundant Array of Independent Devices. Regardless of what you call it, RAID was historically implemented for redundancy or performance. In some of the more recent implementations, both redundancy and performance are implemented.

Given RAID supports redundancy, businesses use it to protect their most important data. To understand how it works, consider that you have a number of different hard disks. These hard disks are combined together to essentially form one storage unit. The data is than broken into blocks and stored on the hard disks. How this data is stored is dependent on which RAID is used. If the RAID supports redundancy, the data will be duplicated, so if a hard disk was to fail it can be recovered. Also, given that data is spread out over the hard disks, it gives performance increases, since multiple hard disks are working at the same time to provide the data.

RAID was originally developed back in the 1980’s. There were many different versions of RAID referred to as levels. Not all the levels of RAID are used, and this video will go through the more common ones.

If your RAID has redundancy, a hard disk can fail and be replaced with no downtime. This is important for businesses, because often the data and downtime is worth more than the equipment itself. If you have 100 people connected to the same server and it fails, that is 100 people who can no longer work. Of course, you could keep a backup of the data, but if you have 100 people waiting for their data to be restored, they may as well take the rest of the day off and come back tomorrow. You can see why RAID for reliability alone pays for itself.

Before I start looking at the different types of RAID, you first need to decide if you are going to use software or hardware RAID.

Software vs Hardware

References
“The Official CompTIA A+ Core Study Guide (Exam 220-1001)” Chapter 6 Paragraph 266 - 276
“CompTIA A+ Certification exam guide. Tenth edition” Pages 303 – 308

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