Answer:
RAID 1 or RAID 5
Step-by-step explanation:
RAID 1 mirrors data across all disks, if you lose 1 disk, you still have 2 copies of that disk.
RAID 5 spreads data evenly across all disks with parity, if you lose 1 disk then lost data can be reconstructed. If you lose 2 disks then all data is most likely lost.
RAID 1 is ideal for important information. RAID 5 is ideal for storage efficiency and security.