ITPEC FE Morning April 2023 Question 15

RAID 0 — striping spreads data across several disks for speed and stores no redundancy.

RAID 0 splits data into blocks and writes them to several disks in parallel, so reads and writes use all disks at once. It keeps no copy and no parity, so the failure of any one disk loses the whole array: it is less reliable than a single disk.

• •RAID 1: mirroring, every write goes to two disks
• •RAID 5: striping with one parity block per stripe, spread over the disks; survives one disk failure
• •RAID 6: striping with two parity blocks per stripe; survives two disk failures

Answer (a)

Why not others:

• •(b) RAID 1 — mirroring spends a whole second disk on reliability; writes gain no speed
• •(c) RAID 5 — adds parity for fault tolerance, and every write must also update the parity, which slows writes
• •(d) RAID 6 — two parity blocks per stripe: more reliable than RAID 5 and slower still on writes

Key rule: Match each level to what it adds (0 striping, 1 mirroring, 5 one parity, 6 two parities); every addition trades speed or capacity for surviving disk failures.

System Component · AI-written, may contain errors