What is the minimum number of disks required for RAID 6?

RAID 6 is designed to provide fault tolerance by allowing the system to continue operating even if two disks fail simultaneously. To achieve this reliable performance, RAID 6 requires a minimum of four disks. This is because two disks are used for storing data, while the other two disks are dedicated to storing dual parity information. The dual parity mechanism allows RAID 6 to rebuild data in the event of multiple disk failures, thus enhancing data protection more effectively than RAID levels that use only single parity, such as RAID 5.

In practical scenarios, the more disks included in a RAID 6 array, the better the performance and redundancy, but the absolute minimum for RAID 6 remains four disks. The other options fall short of this requirement, as two disks would not suffice to implement the necessary parity, and three disks would only support the implementation of RAID 5, which allows for only one disk failure. Therefore, four disks are essential for achieving the intended reliability and fault tolerance of RAID 6.