Fetching Methods - What is the difference between Managed (RPC) , External (RPC) , PDH (RPC) & WMI

Question

First question is what is the default if the default option is set? Next, what is the differences between the RPC listed methods?

I am not sure I ever noticed these as they are only listed in the performance counter monitoring section and not windows service monitor section (where is only has WMI and RPC).

I am wanting to get off of WMI fetching for everything if possible as it is causing more headaches than return on the investment.

bob55 · Answer

There are several fetching methods, because of various OS/environmental issues each of them is having. That's also why fallback mechanism is implemented for this, so if one method fails, another one is used.

* Managed (Default) - calls .Net Framework methods to get performance counter data
* PDH - calls the PDH (Performance Data Helper) Windows API directly from the polling job
* External - polling job calls CounterFetcher.exe utility, this utility calls the PDH API similarly as the method above. PDH library is having known threading issues, so calling it directly from the multithreading polling job can cause polling failures.
* WMI

mwb · Answer

I have the same question.

Prior to the most recent version, the options were definitely limited to RPC or WMI (or inherit from template).  I want to know what the differences are between the RPC methods as well...