RAID 6 is a RAID level that uses disk striping with two parity blocks distributed across all member disks. It can tolerate the failure of up to two disks without losing any data. RAID 6 can provide a minimum of 10TB of usable storage space with five 4TB disks, as the formula for calculating the RAID 6 capacity is (n-2) x Smin, where n is the number of disks and Smin is the smallest disk size. In this case, the RAID 6 capacity is (5-2) x 4TB = 12TB. References: * CompTIA Server+ Certification Exam Objectives1, page 8 * RAID Levels and Types Explained: Advantages and Disadvantages2 * RAID Levels & Fault Tolerance3