Is it true that RAID 6 can allow two disk failures while requiring no less than four disks?

The statement is true. RAID 6 is designed to provide data redundancy and fault tolerance by using two parity stripes. This means that it can withstand the failure of two disks in the array without losing any data, which is a significant advantage over RAID 5 that only supports one disk failure.

To implement RAID 6, a minimum of four disks is required. This is because the data is striped across the disks, and additional space is needed for the two parity blocks. In a RAID 6 configuration, the system utilizes two disks for parity information, ensuring that in the case of a failure of one or two disks, the data can still be reconstructed from the remaining disks. This setup provides a high level of data protection, making RAID 6 a preferred choice in environments where data integrity and availability are critical.

The ability to tolerate two disk failures while requiring a minimum of four disks is a defining characteristic of RAID 6, solidifying its role in data storage solutions where reliability is paramount.