Kevin Holman's OpsMgr Blog : Writing monitors to target Logical or Physical Disks

This is something a LOT of people make mistakes on – so I wanted to write a post on the correct way to do this properly, using a very common target as an example.

When we write a monitor for something like “Processor\% Processor Time\_Total” and target “Windows Server Operating System”…. everything is very simple.  “Windows Server Operating System” is a single instance target…. meaning there is only ONE “Operating System” instance per agent.  “Processor\% Processor Time\_Total” is also a single instance counter…. using ONLY the “_Total” instance for our measurement.  Therefore – your performance unit monitors for this example work just like you’d think.

However – Logical Disk is very different.  On a given agent – there will often be MULTIPLE instances of “Logical Disk” per agent, such as C:, D:, E:, F:, etc…   We must write our monitors to take this into account. 

For this reason – we cannot monitor a Logical Disk perf counter, and use “Windows Server Operating System” as the target.  The only way this would work, is if we SPECIFICALLY chose the instance in perfmon.  I will explain:

Kevin Holman's OpsMgr Blog : Writing monitors to target Logical or Physical Disks