Monitoring and Tuning Your Server

Counting Not-Found Errors

The Web Service performance object includes a counter that displays not-found errors. Not-found errors are client requests that could not be satisfied because they included a reference to a Web page or a file that did not exist. (These errors are sometimes described by their HTTP status code number, which is 404.)

Many not-found errors occur because Web pages and files are deleted or moved to another location. However, some can result from user attempts to access documents that they are not authorized to have. (The code number of these “Access forbidden” errors is 403, and most browsers report them differently from 404 errors. They do not show up in the Not Found Errors/sec counter results.)

You can use the Web Service\ Not Found Errors/sec counter to track the rate at which notfound errors are occurring on your server. Alternatively, set a PerfMon alert to notify the Administrator when the rate of not-found errors exceeds a threshold.

Table 5.15 is a brief description of the Web Service\ Not Found Errors/sec counter.

Table 5.15 Counter for Not-Found Errors

Counter	Indicates
Web Service\ Not Found Errors/sec	The number of client read requests that could not be satisfied because the URL did not point to a valid file. An increase in not-found errors might indicate that a file has been moved without its link being updated. However, it can also indicate failed attempts to access protected documents, such as user lists and file directories.