What is a RAID array and why is it needed?

In the circles of programmers and computer specialists, such a concept as «raid» is well known. This word came into Russian from English and is an abbreviation of redundant Array of Independent Disks. The text translates as follows: an array of independent discs with redundancy.

What is a raid

Raiding – is a technique for combining two data drives into a single array that can be used simultaneously. This means that it increases storage space, allows multiple drives to be used at the same time, and increases the level of data protection and security. This is very important in modern conditions, when the servers store a huge amount of data, they are constantly updated, because they are used by numerous people, if it is a popular site or a popular Internet resource. All this is also very important for the provision of quality hosting services. After all, if the client loses information for one reason or another, the owner of the server will be responsible for it.

It is important to note! The technology provides the possibility of combining not only the same type of data storage, but also different types. For example, one array can include both HDD and SSD data carriers. Systems can have from 2 to 5 or more discs.

The benefits and advantages that this technology provides to the user include:

• expanding the amount of data that can be accommodated in a single repository;
• increased system performance to ensure that more user requests, such as their access to the site, are handled;
• substantial increase in the level of security, data protection. Their simultaneous copying and overwriting of changes on 2 media makes it possible to retrieve information from the second disc if one disc is damaged;
• decreasing cost while increasing storage capacity. A pair of low-cost drives, even with the cost of the embedded chip, will cost less than producing one of the same capacity.

Together, the technology provides improved system performance, reliability and stability.

The types of raids

It is clear that the consolidation of information storage is done using some intermediate element that provides management and control over the operation of the discs. Such an element can be in physical (hardware) or software form.

The hardware version is a chip with an embedded algorithm or program, also called a raid controller. The name speaks for itself. It is installed between the HDD and/or SSD array and the system.

The software option is software that is integrated directly into the processor itself, that is, it uses the processor as a physical medium and the functionality required to make RAID work. It's a virtual control panel of sorts that:

• provides formation of a data array from several data carriers;
• controls his work;
• provides interaction with other elements or units of the device.

The chip, or physical raid can be used with different operating systems, but the software raid must match the host operating system.

What is raid 0, raid 1, raid 5, raid 10, raid 50

Raid – is the common name for different data array technologies. The joining of drives can be done in a variety of ways. Each of these has a different designation that indicates the improvements that will occur when a particular method of combining disc spaces is used.

RAID 0

This method of creating a RAID array is based on the striping principle. This makes it possible to write information to each of the discs. There is no limit to the number of drives. This means you can combine 2, 5, 10  and more drives. This RAID configuration combines all the drives into a single large array to provide the highest speed possible for your disc system.

RAID 1

This method is based on simultaneous copying, writing data only on 2 disc spaces. The same information is stored on them. In this case, the data read speed will be slightly slower than if one disc was running.

RAID 5

This raid provides increased storage reliability. 2/3 of the total capacity will be writable.
This technology allows for a minimum of 3 discs, but the best performance and reliability can be achieved with 5 discs. Speed is medium.

RAID 10

This architecture is based on combining two technologies: 1 and 0. This is encoded in its designation, which should be seen in this way, not as the number 10. It is not something new, but it is a more complex design. It is a 2-tier system. It allows the advantages and benefits of the simpler systems «1» and «0» to be utilised. Half of the total disc space is available. Speed on this raid will be above average.

RAID 50

Like the previous one, this variant is a 2-tier system. But, unlike it, it combines such simpler array technologies as «5» and «0» and has all their advantages. And this is, in particular, a significant increase in performance, improving its reliability in operation and the level of protection, safety of information. The amount of memory to use is 2/3. Synchronisation takes a lot of time.

The advantages and disadvantages of different raids

• 0 – increases capacity and speed, but if one of the discs fails, all information will be lost.
• 1 – provides the usual level of preservation, mirroring 2 discs to each other.
• 5 – provides increased storage reliability, you can use from three discs. 2/3 of the total capacity will be available for writing.
• 10 – allows for increased capacity and storage, while keeping performance at a high level. Half of the capacity of all discs will be available for writing.
• 50 – excellent performance and reliability. 2/3 of the total capacity will be available for storage.