What RAID set should you select for your dedicated server? Before coming to this question, it would be imperative to get a little clarity on what exactly is RAID.

RAID stands for "Redundant Array of Independent Disks".  RAID is a storage technology that links or combines multiple hard drives so that data can be stored on them as if they were one logical unit. In other words, RAID takes multiple physical disks and makes them appear and function as one single drive.

Now, what is a RAID set? RAID set is a secure way to store data in different schemes or architectures that divide and replicate your data among various member physical drives within your RAID array. A RAID set provides important storage characteristics of resiliency, performance, and capacity. As per standard practices, RAID sets range from RAID 0 to RAID 10.

RAID set is an important question we commonly encounter, especially for those clients who are moving to their own dedicated server (or servers) for the first time. Quite common though, also, for clients after they have suffered a critical data loss from a hardware failure. It is important to understand the RAID set ranges before picking up one for your dedicated server or hardware problem mitigation strategy.

So, different RAID sets are discussed as below:

1) RAID 0

RAID 0 involves using 2 or more drives without parity or mirroring i.e. this RAID set offers no redundancy. If one of the member’s drives fails, data on the drives is lost. Obviously RAID 0 is more of figurative significance than of application significance. In fact, for each additional drive that you add to your RAID set, you are mathematically increasing the probability of huge data loss.

Then, why use RAID 0 at all? Simply to gain operational performance without the loss of drive capacity!

2) RAID 1

RAID 1 is data that is written to 2 (or more) drives, mirrored without parity or striping. The member drives in a RAID 1 array essentially producing a mirror of each other. If one of the member hard drives fails, the data in the mirror drive is safe. Obviously, no write performance is gained by the use of 2 member hard drives. In a nutshell, RAID 1 is a simple technology for additional protection of data for dedicated servers.

3) RAID 2

RAID 2 is bit-level striping that is it splits data at the bit level then spreads it over a number of member disks. How is the data read? Disk spindle rotation is synchronized and the data is striped so each sequential byte is on a different drive. RAID 2 technologies require a minimum of 3 member drives - one drive to mitigate data loss and other to gain read performance. The more, the merrier because of the large number of member drives (up to 39!) that could be accessed in parallel and give high performance. RAID 2 is not used much these days as the controllers are rare, complex, and expensive.

4) RAID 3

RAID 3 is byte level striping. This time it’s not the bits but data blocks that are subdivided and stored in two or more drives. RAID 3 requires a minimum of three member drives. RAID 3 is one of the commonly chosen options for managed dedicated servers as it provides large read and write performance gains, especially for large file block transfers. RAID 3 is commonly used in video streaming, publishing and editing. To the flipside advantages, RAID 3 is rather inefficient with smaller files and I/O operations.

5) RAID 4

RAID 4 is block-level striping, similar to RAID 3, except that striping is done on a block-level basis rather than a byte level. It has high read performance as I/O requests are performed in parallel. RAID 4 does not require the spindles of disk to be synchronized as in RAID 3, thus less complex and more economical. RAID 4 is not an option especially when it comes to poor performance of random writing. RAID 4 is not used much in dedicated servers these days.

6) RAID 5

RAID 5 is block-level striping with important feature of independent read and writes operational capability (not in parallel like RAID 3). RAID 5 offers accelerated read performance and is considered to be one of the best all-around systems that combine a high level of security, accelerated performance, and an extremely efficient use of storage. RAID 5 is one of the most popular and recommended solutions for most of the server applications and dedicated server operations.

7) RAID 6

RAID 6 is block-level similar to RAID 5 except that RAID 6 creates two parity blocks for each data block. Thus, a RAID 6 system covers the chances of data loss better than RAID 5. RAID 6 is suited for scenarios where a higher degree of reliability or certainty is required.  For example: databases, applications, E-mail and web servers. RAID 6 is expensive option though as it requires a high availability system.  

8) RAID 10

RAID 10 is a combination of RAID 0 and RAID 1, which is a technology featuring striping of mirror drives. It offers high security by mirroring all data on a secondary set of disks and parallel processing at the same time. This system requires a minimum of four member disks. For RAID 10, the read performance is faster and the storage capacity is less efficient. RAID 10 offers very high performance though it’s one of the expensive storage options.

Which one aligns to my business needs?

This question is not an easy one to answer as it depends on your current state of business and your velocity of expanding your future operations. The selection will also depend on your budget (hardware availability) and at the same time keeping an eye on key goals of performance, resiliency and storage capacity.