Which of the following counters, used to monitor for disk subsystem bottlenecks, is a measurement of the overall size of the I/O operation?

A.
Disk Transfers/sec.

B.
Average Disk sec/Transfer.

C.
Disk Bytes/sec.

D.
Average Disk Bytes/Transfer

Explanation:
The Average Disk Bytes/Transfer counter is a measurement of the overall size of the I/O operation.
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.
C: 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.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 531-533.