A systems administrator is deploying a new storage array for backups. The array provides 1PB of raw disk space and uses 14TB nearline SAS drives. The solution must tolerate at least two failed drives

RAID 0 uses only striping with no parity or mirroring, so a single drive failure destroys all data in the set.

RAID 1 mirrors data across two drives and can survive only one drive failure; it cannot tolerate two simultaneous failures.

RAID 5 uses a single distributed parity block and can survive only one drive failure per set; a second concurrent failure results in complete data loss.

RAID 6 writes two independent parity stripes across all member drives, allowing the array to reconstruct data fully even if any two drives fail at the same time. This dual-parity design is the specific feature that satisfies the requirement of tolerating at least two failed drives in a single RAID set. With large 14TB nearline SAS drives, RAID 6 is especially important because the lengthy rebuild time on high-capacity drives significantly raises the probability of a second drive failure during recovery, a risk that single-parity RAID 5 cannot survive.

RAID 10 mirrors pairs of drives and can survive multiple failures, but only guarantees one failed drive per mirrored pair - two failures within the same mirror pair cause data loss, so it does not unconditionally tolerate two failures within a single RAID set.