A server administrator is configuring 10 web servers, each of which can contain up to four hard disks. To get the HIGHEST level of redundancy for these servers, the administrator should:

RAID 0 uses only disk striping with no parity or mirroring, providing zero redundancy - a single disk failure results in complete and unrecoverable data loss across the entire array.

RAID 5 uses only a single set of distributed parity and can tolerate the failure of only one disk at a time before data loss occurs.

RAID 6 writes two independent sets of parity data across all member disks, meaning any two drives in the array can fail at the same time while the array continues operating and data remains intact and rebuildable. With four disks, RAID 6 guarantees tolerance of any two-disk failure combination, which is a stronger fault tolerance guarantee than RAID 10, where losing both disks in a single mirrored pair causes total array failure.

RAID 10 mirrors disk pairs and guarantees survival of only one failure per mirrored pair - if both disks in the same mirror pair fail simultaneously, the entire array is lost, making its redundancy guarantee weaker than RAID 6.