Back To Basics: Troubleshooting Proxy Server 2.0 -- Part 2 Page 2

Thomas Shinder

Cache (flow) Problems

The Web Proxy services Web Cache is a wonderful thing. If you're in an environment where you have to pay packet charges on data moving through your Internet connection, you can save a lot of money by implementing caching of web pages. The Web Cache can also significantly improve perceived performance on the end user's side, which should help reduce the calls you get regarding the "Internet" being slow.

The Cache works in the background and caches content based on the configuration parameters you've set. The Web Cache configuration sets how aggressively you want caching to be performed, and whether or not you want Active Caching initiated by the Proxy Server. Active Caching will cause the Proxy Server to fetch "popular" web pages in the background, so that these pages have the freshest content. This "fetching" is done during times of low processor usage.

The configuration interface for caching appears below.

The cache expiration policy controls how often the server will send pages back to the user from the cache versus how often it will forward the request to the server on the Internet. The more aggressive caching policies will encourage more cache hits. The drawback is that users may see stale pages more often. The caching feature can always be side-stepped from the client side by hitting the F5 key.

You can see the Advanced Settings for the Web Cache HERE.

The Web Cache doesn't run into problems very often. When there are problems, they're usually related to corruption of some of the files in the web cache. When the Web Proxy service starts up, it always checks the integrity of the web cache. If the cache is large, it may take some time for the Web Proxy service to fully initialize. Keep this in mind if you've configured a very large web cache and it seems like it takes a long time for the service to boot up.

If the Web Proxy service fails to start, check for proxy problems in the Event Viewer. If problems related to cache corruption are mentioned, open a command prompt, change the focus to the drive that contains the cache, and type:

chkdsk /R

This will find and correct file system problems and hopefully fix them. Make sure that the Web Proxy service is stopped when you are performing any of these maintenance tasks! You might also try resizing the cache after performing this operation.

If this doesn't fix the things, you might be experiencing more significant issues with the cache folder hierarchy. In this case, you should disable caching and then delete the cache folder hierarchy. If disk file related problems are getting this bad, you should make sure that the disk is in good shape. If the disk drive is in the process of going belly-up, you should replace the disk before re-enabling the Web Cache again.

This article was originally published on Oct 31, 2000
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