What are good tools/techniques for monitoring and debugging IIS performance problems?

Question

I'm looking for the best tools/techniques for monitoring IIS performance problems and then debugging them. I'm particularly interested in ASP.NET applications.

This may be a combination of tools or there may be something that is good for both?

(I'll add an answer or two based on my experience, for my future reference!, but I hope I'll get some other answers with useful tools to add to my collection)

Answer 1

PerfMon is a good basic tool for monitoring.

There are a number of key performance monitor counters that can be used for keeping an eye a server.

A useful article by Microsoft's Thomas Marquardt suggests the following as the minimum counters that should be used for monitoring an ASP.NET application

• Processor(_Total)\% Processor Time
• Process(aspnet_wp)\% Processor Time
• Process(aspnet_wp)\Private Bytes
• Process(aspnet_wp)\Virtual Bytes
• Process(aspnet_wp)\Handle Count
• Microsoft® .NET CLR Exceptions# Exceps thrown / sec
• ASP.NET\Application Restarts
• ASP.NET\Requests Rejected
• ASP.NET\Worker Process Restarts (not applicable to IIS 6.0)
• Memory\Available Mbytes
• Web Service\Current Connections
• Web Service\ISAPI Extension Requests/sec

One counter that I have found useful that isn't mentioned in that article but is discussed in a Thomas Marquardt blog post on ASP.NET Thread Usage is this one:

• ASP.NET Applications\Requests in Application Queue

Answer 2

Here's a list of "Useful tools and add-ons for IIS troubleshooting and IIS7"