ITPEC FE Morning April 2020 Question 14
ITPEC FE Morning April 2020 — Question 14 of 80
RAID 6 usable capacity — calculate data storage with dual parity.
Formula: usable = (N - 2) × drive_size
For 6 drives × 1 TB each:
- RAID 6 reserves 2 drives for parity (double fault tolerance)
- Usable capacity = (6 - 2) × 1 TB = 4 TB
Why not others:
- (a) 3 TB — would apply if a hot spare were reserved, but the question states no spare disks
- (c) 5 TB — RAID 5 formula (N - 1), which uses only single parity
- (d) 6 TB — RAID 0 (no parity, no redundancy)
Key rule: RAID 6 = dual parity → subtract 2 drives. RAID 5 = single parity → subtract 1.
AI-generated — may contain errors
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