I'm investigating an issue where a user is uploading a large document to the web server. This is resulting in a time out at their end. However I'm wondering if it is possible to detect this from the server in order to determine if other users are affected.
There is a connection made while the document is being uploaded. So I'm wondering if IIS 6 is able to detect and record or log anywhere when a client request has timed out?
IIS logs connection timeouts to the HTTPERR log. It should be in C:\WINDOWS\system32\LogFiles\HTTPERR
Here is a KB article describing what is available in HTTPERR: http://support.microsoft.com/?id=820729
(as Sam said though - if the problem is client side, it won't show up in an IIS log)
It depends what you mean by times out. If a client request times out because it cannot connect to the server, or doesn't get a response, this is a client thing, IIS know nothing about it.
If the reason for the time out is an error on the server side, say with a script, then IIS will log this error, but not a timeout.
I would use a transaction monitoring service to log the issue from the user side. Use either the iMacros Firefox addon and run the test on your machine, or get a free account at AlertFox and run the test there.
Note that the default IIS timeout is only 120 seconds, so it is likely you will need to increase this to accomodate larger files. See Setting Connection Timeouts to Save Resources (IIS 6.0) for more information and how to set the connection timeouts for IIS 6.0.