A RAID 1 array is the linkage of at least 2 hard drives. It saves the same data on both hard drives with full redundancy. The capacity of the array is limited to the smallest drive involved. With 2 hard drives, the storage space is reduced by half. RAID 1 is the simplest RAID method: both drives are written identically; if one fails, the other provides all data. The protection against failure is high, because data is lost only if both drives fail.