PhysicalDisk perfmon counters versus LogicalDisk counters RRS feed

  • Question

  • Hi,
    We have a Physical disk which is partitioned into 4 drives,D,E,F,J.We are using Windows server 2003. I am monitoring individual logical disk idle time and physical disk idle time. These are a day's average values

    Counter	                                  Value
    LogicalDisk(D:)\%idle time	        84.92676725
    LogicalDisk(E:)\%idle time	        87.60788474
    LogicalDisk(F:)\%idle time	        94.81640539
    LogicalDisk(J:)\%idle time	        98.49689629
    PhysicalDisk(1 D: E: F: J:)\%idle time	74.4477885

    I noticed PhysicalDisk valueis much lower than average of LogicalDisk values,even though LogicalDisk values look good. PhysicalDisk value is suppose to be average of LogicalDisk values right? Why this variation caused?

    Thank you

    Monday, June 17, 2013 11:55 AM


  • This is expected if you have a partitioned drive. The numbers are not averaged but multiplied when calculating probability of independent events. Of course your sever could have correlated disk io across multiple partitions, that would make the number off a little bit. 

    This forum is for a graphics library that can only be used to write user interface in a software, if you need more help in monitoring your server performance, visit the windows server forums on technet.

    Visual C++ MVP

    • Edited by Sheng Jiang 蒋晟 Monday, June 17, 2013 7:34 PM
    • Proposed as answer by Barry Wang Wednesday, June 19, 2013 9:23 AM
    • Marked as answer by Barry Wang Wednesday, June 19, 2013 9:23 AM
    Monday, June 17, 2013 7:34 PM