Basic Computing

What is hard drive raid and what are they for?

We will know in this article what Raid is, it  is an array of redundant independent disks, it is a term that is used in the computer world, we will provide you with information regarding its conception, as well as its usefulness. external hard drive raid

What is raid? external hard drive raid

Raid, is a word that belongs to the world of computing that involves the hardware part. It is a term that originates from the English language  Redundant Array of Independent Disks, and translated into Spanish means: array of redundant independent disks, it is good to note that not all Raid systems provide redundancy, which we will learn in the next few paragraphs.

The objective of a disk Raid system is to safeguard the information if the hard disk fails, on certain occasions it works to improve the reading speed of various disks that make up a single volume. external hard drive raid

It consists of creating a single volume with different hard drives that work together, and in this set you can obtain redundancy, that is, fault tolerance in case one does not respond, it is known as disk mirroring, or also as higher speed, the same is known as disk striping, which makes the whole set work in tandem.

external hard drive raid
external hard drive raid

It can be concluded that it is a storage method, which are composed of levels and are numbered from 0 to 9, some of these are more useful than others. external hard drive raid

Each level is a different method, it allows organized storage, some can be combined with each other, which generates a two-digit Raid level, such as Raid 10, which is sometimes identified as Raid 1 + 0. Each level of Raid has its own advantages and disadvantages.

What is it for?

It is a technique called striping, which serves to divide information prior to distribution in the blocks where they are stored, doing it in an organized manner on the various disks of the array.

You have to have a Raid system, it can be internal or external and its hardware or software execution, in this case, is carried out by the Bios of the operating system to control the Raid, where the hard drives could be IDE or SATA. external hard drive raid

Benefits and advantages external hard drive raid

external hard drive raid
external hard drive raid

Hard drives are technically characterized by their elements that they contain called MTBF, Mean Time Between Failure or mean time between failure, these provide great value to the hardware part. It is essential to point out that the MTBF alerts the user of what types of discs can be used, as well as which ones can be functional at times, data loss may occur or it does not allow the user to enter the information.

Apart from solving the previously mentioned problem, a storage system that is based on a Raid architecture, provided four advantages, namely:

Great performance and capacity to transfer information more than individual disks as a result of read, record operations that are performed simultaneously on hard drives in parallel.

Similarly, large storage capacity of individual disks. An “array” of a disk can be seen as a logical disk composed of the sum of the individual disks, most of the configurations and the total capacity is higher.

Great integrity, when an error arises in the data stored on some of the disks of the “array”, data corruption, recording error, among others, the parity information produced by the Raid systems, access to reconstruct the data that has been lost. , maintaining the integrity of all the information stored.

How a Hard Drive Raid Works

It can be said that it has the function of placing the information contained in several hard drives, in addition to allowing the input and output (I / O) operations to work in a balanced way, making the performance more effective. external hard drive raid

That is to say, that the data is recorded on the hard drives at the same time, or just as data is recorded on one of them, and another data on another disk to share the work. Raid systems are shown in the operating system as if they were a single logical disk, since they summarize in a single volume.

For a Raid system to function, it requires the presence of a Raid controller, which can be hardware or software. Currently, most of the PCs that users have, have a software Raid controller that is integrated into the BIOS of the motherboard.

What types are there? external hard drive raid 

Currently there are a wide variety of types, it is important to note that many are outdated due to their limited usefulness compared to others, but it is essential that the user knows the most common ones.

RAID 0 external hard drive raid

It is a type of Raid, known as the main one, which has the mission of providing great speed to the system. The data is being recorded on two hard drives in parallel, which translates from one bit to another, so that the bandwidth can be said to be double and for this reason it provides remarkable performance.

It also has the ability to double the volume, which means that if you use two hard drives of 1 TB each, you get a volume of 2 TB. The compensation of this type of Raid, is that if in the event that one of the two hard drives fails, the stored data of the two would be damaged, because it is shared between the two drives.


It is a basic type of Raid, and it handles the main concept of redundancy. Thus, the data is recorded on the two hard drives simultaneously, that is, one is a true and exact copy of the other, known as “mirroring” mode.

In this particular case, if one of the two disks were to be damaged, there would be no risk of losing the data, because they are stored on the other, you only have to replace the damaged disk with a new one, what you have to do is to reset the Raid 1.

The only flaw that this Raid mode shows is that no performance is obtained, quite the opposite, because all information must be registered twice. Just as the size of the volume corresponds to the one with the smallest capacity; So, in the case that a 1 TB disk and an additional GB disk are used, we have a 500 GB volume in a Raid 1.


This type is the most used mode nowadays, because it allows any number of hard drives, with a minimum of three, and only one of the drives will be used as a “backup”, which means that only the capacity will be wasted. Of one of them.

In Raid 5, the volume read production increases, multiplied by the number of disks that make up the Raid, except for one of them. Which means, that in the case of having 5 hard drives in Raid 5, the speed is multiplied by 4.

It should be taken into account that it presents a fault tolerance of a disk: in the event that a disk fails, there is no risk of losing anything, just proceed to change the disk and everything will be fine.

The disadvantage that this system presents in hard drives is that in the event that two drives fail, we could lose data.

RAID 1 + 0 and other types

On the market, there are other types, but the vast majority are a combination of all of the above. You can say, as an example: a Raid 1 + 0 system that involves first making two Raid 1s, and then a Raid 0 between them, resulting in a total of 4 hard drives, 2 fault tolerance drives, one per each Raid 1, and in Raid 0 with greater speed.

Certainly having the Raid 5, it is a type that is not used today, because more discs are wasted, you get less tolerance and less speed.

However, it is important to make it known that the only one that is used mostly, and only in companies, is Raid 6 mode, it refers to a variant of Raid 5, but uses two disks as backup instead of one, and with higher speed.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button