Data Security : Raid explained

Data Security is critical

When you decide to equip yourself with a NAS server, you will necessarily have to ask yourself the question of the level of RAID to adopt. Why? Because it secures your data in case of failure of one of the hard disks and it is one of the biggest avantages des serveurs NAS. All the boxes with at least 2 bays offer at least one type of RAID. The question is which RAID to choose to maintain the balance between performance and data protection.

What is Raid?

RAID is traditionally used in companies where performance optimization and data protection are essential. But with the development of the NAS market for home users and the increasing data storage needs of consumers, RAID is also making its way to us.

The acronym RAID first appeared in an article published in 1987 by the University of Berkeley entitled A Case for Redundant Arrays of Inexpensive Disks (RAID. The cost of data storage is no longer such a problem today, so the acronym has evolved to “Redundant Array of Independent Disks”.

This refers to the types of data distribution over multiple hard drives that aim to improve their performance or fault tolerance, or both, while ensuring the security of the recorded data.

The type of RAID defined depends on the data protection you want to adopt and the use you will make of it.

The different type of Raid for a Nas server


raid 0 system explainedRAID 0 is the protection type……. level 0. It is chosen by those who seek performance first and foremost. The data is written to several disks considered as a single volume. All discs can work at the same time and increase the read/write speed proportionally. However, the failure of a single hard disk will result in the loss of all your data.

Storage capacity is added between each disk unless you have a smaller disk size. In this case, the capacity of each disk will be limited to the size of the smallest disk. For example if you have 2 hard disks of 2TO and 2 hard disks of 1TO, the available volume will not be 2+2+1+1+1 or 6 TO but only 1+1+1+1 or 4 TO.

Not so interesting, is it?


JBOD for “Just a Bunch Of Disks” assembles all the disks into a single storage volume. But unlike RAID 0, the data is not distributed between the disks but recorded separately from one disk to another. In the event of a failure of one of the disks, you will only lose the information saved on that disk.

The volumes of each disc add up, regardless of the size of each disc. However, you will not benefit from the performance of RAID 0.


raid 1RAID 1 is a kind of mirror backup. Data is recorded simultaneously from one disc to another, generating a replica of everything you do. If one of the discs fails, you can continue to work with the other. This is the simplest method of data protection. Be careful not to inadvertently delete a folder, however, as the action will be reproduced on the other disk.

The most constraining aspect is that you divide your storage capacity by 2 since all your data is duplicated.


raid 5RAID 5 is the configuration that offers the most benefits. This level offers better performance than RAID 1 mirroring while protecting your data. However, you will need a NAS with at least 3 hard disks. The total size of the storage volume is the capacity of the smallest disk multiplied by the number of disks minus one. If you have 4 disks of 1TB configured as RAID 5, you will have 3TB of available space.

The volume removed is used as a “parity” divided on all discs. This parity makes it possible to rebuild the contents of the disks if one of them were to fail. The system continues to operate while you replace the disk with reduced performance.


raid 6RAID 6 is identical to RAID 5 but provides even more security because instead of using one parity block, it uses two. You can have two failed disks without losing data.

Operation in RAID 6 requires at least 4 hard disks.

RAID 10 is a combination of RAID 1 and RAID 0 also called RAID 1+0. 4 is the minimum number of disks, you can set 2 disks to RAID 0 to take advantage of the performance gain to work on temporary files for example and secure your data on 2 mirror disks with RAID 1.


raid 10The choice of RAID is not crucial because it can be modified in the settings of your NAS. However, a bad choice and failure of your system can have serious consequences on your productivity or on the backup of your data. So take the time to choose a RAID that will allow you to protect your most important data and take into account the space consumed when choosing your hard drives.

Don’t forget one important thing. Setting up your disks as RAID does not mean securing your data. In the event of fire, theft, etc., your data may be lost forever. So don’t hesitate to back up your data from time to time to an external hard drive that you keep in a place other than your NAS or to use the automatic backups to online clouds offered by most NAS.