Which of the following would not cause a bottle neck, but slow down the system?
A.
Average Disk Queue Length
B.
Disk Transfers/sec
C.
Current Disk Queue Length
D.
Disk Bytes/sec
Explanation:
If this value is over 80 for a physical disk and the average disk/sec transfer is less than acceptable, the disk drive will slow down the overall system performance.
Incorrect Answers
A: If the value of the Average Disk Queue Length is more than 2 for a single disk drive, and the percentage of disk time is high, the selected disk is becoming a bottleneck to the system.
C: If the value of the Current Disk Queue Length is more than 2 for a single disk drive over a sustained period, and the percentage of disk time is high, the selected disk drive is becoming a bottleneck.
D:
Disk Bytes/sec is the rate at which bytes are transferred. Add up this counter’s values for each disk drive attached to the same SCSI channel, and compare it to the throughput of the SCSI bus. If this summed value is close to 80% of the throughput for the SCSI bus, the SCSI bus itself is becoming a bottleneck.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, p. 347