IIS Performance Counters
Performance counters measure quantities of information or data, according to the number, size, duration, and rate of data being requested or received. You should not expect to get a list of details from a counter, such as a list of error messages. Instead, use performance counters to get quantities, such as the number of error message since startup or the rate at which error messages are being generated.
You can access counter data through the System Monitor or through the Simple Network Management Protocol (SNMP) service (search for System Monitor or Performance Monitor and SNMP in Help and Support).
For a list of IIS performance counters and their definitions, see the section titled "Performance Counters Reference" in the IIS administration guide that is included with IIS. Or, see the topic Performance Counters Reference on the Microsoft TechNet Web site.