Virtual Performance Counters are a special type of counters that are used only within NetCrunch. They are referred to as virtual since they do not actually refer directly to an existing performance counter that is monitored. It would be more appropriate to call them Calculated Counters .
They are used in creating custom counters, defined by a simple or compound arithmetic expression consisting of variables (using addition, subtraction, multiplication, division and MIN or MAX functions), to which real collected data from monitored device counters (of SNMP, Windows, Linux, Mac OS X, BSD or NetWare type) are assigned.
In a Virtual Counter definition you can only use real monitored performance counters of one type (i.e. SNMP, Linux, Mac OS X, BSD, NetWare or Windows) as an arithmetic expression variables.
You define a Virtual Performance counter using the program wizard.
During the definition of a Virtual Performance Counter, if instances are used, you must point to a virtual instance of the selected real monitored counter called VCounter that will be used in actual arithmetic expression as a variable. Later, you can use the created virtual counter regularly just as any counter in threshold definitions, trend viewer, reports or events - it always starts with .NCVC to distinguish it from regular device counters.
Note Please note that you may not delete a virtual performance counter definition if it is already being used somewhere in the program.
