A certain application initially uses 1TB of drive space, but this is expected to double each year for the next two years. Which of the following is the minimum number of 1TB drives that are needed…

The correct answer is C. 5. After two years of annual doubling, the storage requirement grows from 1TB → 2TB → 4TB. RAID 5 uses one drive's worth of capacity for distributed parity across all drives, so usable capacity equals (n - 1) × drive size, where n is the number of drives. To achieve at least 4TB…

Server hardware installation and management

Question

A certain application initially uses 1TB of drive space, but this is expected to double each year for the next two years. Which of the following is the minimum number of 1TB drives that are needed in a RAID 5 configuration?

Options

How the community answered

(34 responses)

A
6% (2)
B
9% (3)
C
82% (28)
D
3% (1)

Explanation

After two years of annual doubling, the storage requirement grows from 1TB → 2TB → 4TB. RAID 5 uses one drive's worth of capacity for distributed parity across all drives, so usable capacity equals (n - 1) × drive size, where n is the number of drives. To achieve at least 4TB of usable space with 1TB drives: with 5 drives, usable capacity = (5 - 1) × 1TB = 4TB, which exactly meets the requirement. With 4 drives you would only get 3TB of usable space (insufficient). With 3 drives you get 2TB (also insufficient). Therefore, 5 drives is the minimum to satisfy the projected 4TB need in a RAID 5 array.

Topics

#RAID 5#Storage capacity planning#Drive space calculation#Server storage

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