Simply put, Uniform Resource Identifier (URI) cache stores information about a website address. This information includes a set of characters used to identify the website/URL. When it comes to monitoring the Internet Information Server (IIS) performance, the URI cache is a critical component to be monitored along with the hardware, website availability, Web transaction responsiveness, and others.
Relationship between Caching and IIS
Caching improves process requests and increases response times for frequently requested data from the IIS Web server. By not caching, IIS has to read the information from websites every time the same request is made. This also leads to a delayed authentication process.
Importance of Monitoring IIS Counters
There are different counters in the IIS server and you can monitor them to improve the server’s performance. If you don’t monitor these counters, then you won’t know which problem occurs. For example, you may not know if your users are having problems connecting to the server, you may not know if there are hardware problems, or any problem with the Web application that is causing the issue, and so on. These metrics provide critical information about user-requested data. More specifically, you can measure the performance of the counters and really look at the quantity of the data and its attributes such as size, duration, and the rate at which data is being requested and received.
IIS has the following performance counters:
- Web Service Counters
- Web Service Cache Counters
- Port Monitoring Counters
- System Monitoring Counters
URI Performance Counters
It is important to monitor URI cache counters because they provide performance metrics in order to optimize Web servers, Web applications, and websites. URI cache counters are part of the Web service cache counters. The URI cache counters consists of cache performance counters that process information about the data being requested from the Web server. Web services’ URI cache counters are designed to monitor server performances only, and you cannot configure them to monitor individual websites. A server management tool usually monitors the server performances and the following URI cache components within the IIS environment:
- URI Cache Flushes Counter: Counts the number of URI cache flushes that have occurred since the server started. If a response is taking more time than what is specified in the threshold, or if the file was edited or modified then this counter will flush those files.
- URI Cache Hits Counter: Counts the number of successful lookups in the URI cache since the server started. The value of this counter should increase constantly. If the value that is shown is very low, then you could inspect why requests are not finding cached response.
- URI Cache Hits Percent Counter: Calculates the ratio between URI cache hits to the total number of cache requests. For example, if approximately one-fifth of requests to your sites are for cacheable content, then the value of this counter should be close to 20%.
- URI Cache Misses Counter: Counts the number of unsuccessful lookups in the URI cache. If the value of the count is high, and the value of the cache hits is low, you could inspect why the responses are not cached.
In general, IIS performance monitoring ensures:
- Performances of your Web servers, websites, and Web applications are optimized
- Monitor your server hardware in case of any failure
- Alert arrive when problems are detected
- You remain vigilant about the overall IIS server performance
- That you understand how your Web servers are performing
SolarWinds server monitoring software comprehensively monitors your IIS web servers and its components. It provides insights on what to monitor in your servers and leverages Microsoft® recommendations for threshold values of components.
If you haven’t experienced Server & Application Monitor, you can always try the fully functional free 30 day trial kit.