Nested RAID Levels

In my previous article I explained what RAID means, why is it being used and showed some of the more traditional levels. Now it's time to introduce the nested RAID or 'Hybrid' levels. The origin of the name is from combining two or more of the standard levels to gain performance, additional redundancy or even…

In my previous article I explained what RAID means, why is it being used and showed some of the more traditional levels. Now it's time to introduce the nested RAID or 'Hybrid' levels. The origin of the name is from combining two or more of the standard levels to gain performance, additional redundancy or even both.

RAID 0 + 1 – is a mirror of stripes. It combats stripping of the data (Like level 0) and mirroring the stripped data (like level 1) to combine the advantages of both without the disadvantages of both. The minimum required amounts of drives are 4 and it can be done only on an even number of drives.

The formula is: Capacity of all drives / 2

RAID 1 + 0 – is a stripe of mirrors and it's a reversed 0 + 1 RAID. This is the RAID that is mainly used these days and supported by the more sophisticated controllers. This level is considered to gain the best throughput performance as it utilizes the performance of RAID 0 and it's a perfect choice for I / O intents applications such as Database servers. This level mirrors and information across half of the drives and stripes it across the other half providing both great performance and redundancy. RAID 1 + 0 requires a minimum of 4 drives and will use half of the capacity to operate.

The formula is: Capacity of all drives / 2

RAID 5 + 0 – This level combines the straight block level stripping of RAID 0 with the distributed parity of RAID 5. It requires at least 6 drives. The way it works is the same as RAID 5, using a XOR table for parity but this RAID level uses two XOR parity tables in a single block level stripping, providing double the redundancy of a RAID 5 with the great performance of RAID 0.

The formula is: Capacity of one drive * (Number of Drives -2)

RAID 6 + 0 – Combines the straight block level stripping of RAID 0 with the distributed double parity of RAID 6. It is a RAID 0 array stripped across a RAID 6 configuration. It requires at least 8 drives and the way it works is using two XOR parity tables like RAID 5 and an additional two parity calculations of the “Galois fields” formula.

The formula is: Capacity of one drive * (Number of Drives – 4)

Well this covers this article about nested RAID levels. There are more levels out there such as 5 + 1, 6 + 1, 100, and more but it's very unlicensed you will ever encounter those. My series of articles regarding these RAID levels should give you the ground to know better and to choose the right configuration for you.

Thank you for reading and I will see you in my next nugget.