A number of logical disk operations should be documented for the baseline. When

which of the following has a value over 80% would you need to be wary of disk response time reaching unacceptable levels?

A.
The percentage of disk time for all disks that contain the Pagefile.sys.

B.
The percentage of disk time for all disks other than those that contain the Pagefile.sys.

C.
The Current Disk Queue Length disk counter.

D.
The Average Disk Queue Length disk counter.

Explanation:
When the percentage of disk time for all disks other than those that contain the
Pagefile.sys, is over 80%, you would need to be wary of disk response time reaching
unacceptable levels. You should start monitoring disk counters such as the Average Disk Queue Length disk counter and the Current Disk Queue Length counter to isolate the issue.
Incorrect
Answers:
A: The percentage of disk time for all disks that contain the Pagefile.sys should be
monitored and documented for the baseline because you can use these values to determine whether the server is paging a considerable number of memory requests to disk. When the available bytes are around 4 MB, and pages/sec is high, then a memory bottleneck has occurred.
C: The disk has become a bottleneck when the Average Disk Queue Length disk counter’s value is greater than 2 for a disk drive and the percentage of disk time is high.
D: The disk has become a bottleneck when the Current Disk Queue Length disk counter’s value is continuously greater than 2 for a disk drive and the percentage of disk time is high.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 348-349.