Which of the following counters, used to monitor for disk subsystem bottlenecks, indicates the rate at which bytes are transferred, and can be said to be the primary measurement of disk throughput?

A.
Disk Transfers/sec.

B.
Average Disk sec/Transfer.

C.
Disk Bytes/sec.

D.
Average Disk Bytes/Transfer

Explanation:
The Disk Bytes/sec counter shows the rate at which bytes are transferred. This counter can be regarded as being the primary measurement of disk throughput.
Incorrect Answers:
A: The Disk Transfers/sec counter indicates disk utilization as the number of read/writes requests completed per second.
B: The Average Disk sec/Transfer counter indicates how fast data moves through the system as an average time of each data transfer for read/write requests.
D: The Average Disk Bytes/Transfer counter is a measurement of the overall size of the I/O operation.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 531-533.