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SG0-001 · Question #484

The specification of disk drives used in a storage system lists an average of 200 read IOPS per drive. Which of the following should be expected of an 8 drive RAID 5 array?

The correct answer is C. 1400. An 8-drive RAID 5 array with 200 read IOPS per drive is expected to yield 1400 read IOPS, as one drive is dedicated to parity.

Storage Functionality

Question

The specification of disk drives used in a storage system lists an average of 200 read IOPS per drive. Which of the following should be expected of an 8 drive RAID 5 array?

Options

  • A1000
  • B1200
  • C1400
  • D1600

How the community answered

(30 responses)
  • A
    3% (1)
  • B
    3% (1)
  • C
    83% (25)
  • D
    10% (3)

Why each option

An 8-drive RAID 5 array with 200 read IOPS per drive is expected to yield 1400 read IOPS, as one drive is dedicated to parity.

A1000

This value is incorrect as it does not align with the standard RAID 5 read IOPS calculation of (N-1) * per-drive IOPS.

B1200

This value is incorrect as it does not align with the standard RAID 5 read IOPS calculation of (N-1) * per-drive IOPS.

C1400Correct

In a RAID 5 array, one drive is used for parity, so an 8-drive array has 7 data drives available. For read operations, all data drives can contribute, thus the total read IOPS is calculated as (Number of drives - 1) * IOPS per drive, which is (8-1) * 200 = 7 * 200 = 1400 IOPS.

D1600

This value incorrectly assumes all 8 drives are contributing to data reads, disregarding the single parity drive in a RAID 5 configuration.

Concept tested: RAID 5 read IOPS calculation

Source: https://learn.microsoft.com/en-us/windows-server/administration/performance-tuning/subsystem/disk-overview

Topics

#RAID 5#IOPS calculation#storage performance#disk arrays

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