CompTIA Server+ (SK0-005)Server Hardware Installation and ManagementMedium
A server has eight 2TB drives configured in a RAID 6 array. What is the total usable storage capacity of the array?
- A14TB
- B10TB
- C12TB
- D16TB
Show answer & explanationAnswer & explanation
Correct answer: C. 12TB
RAID 6 uses double distributed parity equal to two drives' worth of capacity. Usable capacity = (n-2) x drive size = (8-2) x 2TB = 6 x 2TB = 12TB.
Why the other options are wrong
- A. Would only reserve one drive for parity, which describes RAID 5, not RAID 6.
- B. Would correspond to reserving three drives for parity, which is not how RAID 6 works.
- D. This is the raw total capacity with no parity overhead subtracted.
RAID 6 Capacity Calculation
RAID 6 stripes data with double distributed parity across all drives, tolerating two simultaneous drive failures at the cost of two drives' worth of capacity.
- Usable capacity = (n-2) x drive size
- Requires a minimum of 4 drives
- Can survive two simultaneous drive failures
Memory trick: RAID 6 always gives up two drives to double parity guards.