Which RAID levels add parity for redundancy with a trade-off in write speed?

• A. RAID 5 and RAID 6.
• B. RAID 0.
• C. RAID 1.
• D. RAID 10.

Answer: (A)

Parity-based redundancy is about using extra parity data to recover lost information. In RAID levels that include parity, data and parity blocks are spread across multiple drives. When you write new data, the system must calculate and update the parity for the affected stripe as well as the data, which adds extra write work. That extra parity calculation and writing slows down writes compared to configurations that don’t use parity.

RAID 5 uses a single parity block per stripe and can tolerate one drive failure; RAID 6 adds a second parity block, giving protection against two simultaneous failures. Both provide redundancy with better storage efficiency than mirroring, but the write operations incur a penalty due to updating parity. In contrast, RAID 0 has no redundancy, RAID 1 relies on mirroring (no parity), and RAID 10 combines mirroring with striping but doesn’t use parity for fault tolerance. Hence, parity-based levels with a write-speed trade-off are RAID 5 and RAID 6.