Topic Last Modified: 2007-05-16

You can compare actual usage to available resources to determine whether a resource shortage is imminent. To monitor Windows Server 2008 SMTP Server capacity, review both the physical resources and the SMTP service capacity. A physical resource reaches capacity when it is busy 100 percent of the time. A service reaches capacity when requests for service start experiencing delays.

The following table describes the objects to monitor and counters to use.

Object Counter Normal readings Description

Logical Disk

%Disk Time


This is the percentage of elapsed time that the selected disk drive is busy servicing read or write requests. If readings continuously exceed 70 percent, consider adding another SMTP server.


% Total Processor Time


This is the average percentage of time that all the processors on the system are busy executing non-idle threads. On a multiprocessor system in which all processors are always busy, this is 100 percent. If all processors are 50 percent busy, this is 50 percent. If one-fourth of the processors are 100 percent busy, this is 25 percent. It is the fraction of time that is spent doing useful work. Each processor is assigned an idle thread in the idle process that consumes those unproductive processor cycles not used by any other threads.


Available Bytes

>10% of total memory

This displays the size of the virtual memory currently on the Zeroed, Free, and Standby lists. Zeroed and Free memory is ready for use, with Zeroed memory cleared to zeros. Standby memory is memory that is removed from a process Working Set but still available. Notice that this is an instantaneous count, not an average over the time interval.