IIS is very popular in part because it provides such a compact service with lots of features and configurations. Most enterprises that use Windows Server editions are hosting their websites using IIS. When hosting critical applications, many companies use monitoring software to keep their system administrators informed about the overall behavior of their systems. Such software provides configurable alerts for performance counters, services and applications. We will talk about how to monitor IIS, what the most important performance counters are, and what services should be monitored when talking about Internet Information services.

IIS can send information about its application pools and worker processes, active requests, sites and applications, services that depend on it, logging information, abnormal behavior and so on. You should configure your monitoring software to measure the amount of CPU and memory percentage that IIS is using. Worker processes are responsible for executing code for web applications, sending and responding to requests and so on. Each worker process should be monitored carefully so that the following parameters are working as desired:

Listed below are some of the recommendations for monitoring the Internet Information Services (IIS) counters and services.
IIS Services

Monitoring services is very important in case of business critical applications and IIS is one of those critical services that should be monitored. An IIS failure can be the root cause for other applications failing and the cause of many hours looking in log files for the cause of the failures. Below are three important IIS services that should be monitored.
Services to Monitor

Services Service Name
Application Host Helper Service AppHostSvc
Windows Process Activation Service* WAS
World Wide Web Publishing Service W3SVC

• The Windows Process Activation Service also has some Event IDs that should be monitored as well. The Event Source for the following Event IDs is the Microsoft-Windows-WAS log file. The Event Log Monitor is ideal for this task. - (Error): WAS is not able to enable application pool. - (Error): Application pool is being automatically disabled. - (Error): WAS encountered a failure when it started a worker process to save the application pool. The application pool has been disabled. - (Warning): A worker process serving application pool has requested a recycle because it reached its private bytes memory limit. - (Warning): A worker process serving application pool has requested a recycle because it reached its virtual memory limit. - (Warning): A process serving application pool terminated unexpectedly.

IIS Counters

Internet Information Services (IIS) has many counters that can be monitored on a running. Each of the following counters below are counters that are recommended to be monitored for the performance of your IIS process.