Logical/Physical % Disk Time is very High!!

hi friends, have question.

actually, i'm monitoring several servers using windows performance monitor tool.  so, when observed a result 1 server and i encountered logical disk_% disk time counter value was  906,940,628.427 %!!!.  before generate general report, clicked radio button called "average", because wanted average counter.  next, i put counter processor_%privileged time , counter showed 0.733% (that´s normal). so, wrong %disk time counter?.

greetings , help.

aleds

pd: it´s same case physical disk% disk time counter.

hi,

thanks posting.

this behavior can occur because controllers allow operation system use overlapping input/output operations multiple outstanding requests. disk performance counters time responses using 100 nanosecond precision counter, , report cumulative statistics given sample time. sample time go on 100 percent if, example, have 10 requests completed in 2 milliseconds each in 10 millisecond sampling interval. if have multiple disks in raid arrangement, overlapped input/output happens because os can read , write multiple disks, , show value higher 100 percent counter.

an accurate way examine or monitor disk usage (basy) time measure disk latencies. typically, if value of 1 of following counters larger 20 ms, disk over-loaded:

• avg. disk sec/read
• avg. disk sec/write
• avg. disk sec/transfer

it important note %disk time description there incorrectly states registry key clamp values @ %100 exists misleading.

for more information please refer following ms articles:

% disk time may exceed 100 percent in performance monitor mmc
http://support.microsoft.com/kb/310067
performance monitor , % disk time
http://social.technet.microsoft.com/forums/en-us/winserverhyperv/thread/6a62ed7c-e2ad-4640-bf35-f47c724701db/
examining , tuning disk performance
http://technet.microsoft.com/library/cc938958

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lawrence

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