Help with Windows Perfmon

Question

I want to understand how well Windows Server performs under certain application loads.

Generally I want to check how CPU, memory, network and HDD are performing. What counters should I check and what are the advisable values for those counters.

Answer 1

The five counters I find most useful for these things are:

• CPU: System\Processor Queue Length. Divide the current queue length by the number of CPU cores in the system. If the result is less than 10, your CPU is in good shape - even if it is running at 100%. Though at 100%, it wouldn't take much more load to swamp the system.
• Memory: Memory\Pages Input/Sec. This shows how often the system has to read things from disk (a file, or virtual memory) that it wanted to have ready in RAM. Now, many things first get to RAM by being read from disk, so some spikes are common. But if the system isn't doing a lot of work that naturally reads constantly from disk, these spikes should be short, and the counter should regularly return to zero.
• Network Input: Network Interface\Packets Received Errors\NIC name. If you're seeing more than the occasional error, you should be looking for problems in your NICs, your switches, or your wiring.
• Network Output: Network Interface\Output Queue Length\NIC name. The number of packets waiting to be sent. If this consistently goes above 2, you have a network bottleneck and should be looking to resolve network issues or add bandwidth.
• Disk Utilization: PhysicalDisk\Current Disk Queue Length\driveletter. Divide this by the number of spindles you have. If the resulting number is higher than 3 (and stays that way for long periods), something is asking for data faster than the disk (or array) can provide it. Consider lowering demand on the disk, or getting a faster disk system. I saved disk for last because it is the most common sign of a bottleneck. Sometimes a high disk queue length is really a sign of a memory shortage - you'll see Pages Input/Sec go way up, too.

For more detail, see my article: Windows Perfmon: The Top Ten Counters