Windows Server 2008R2 IIS7.5, Requests getting 401 status

We have a web site running in windows server 2008r2 iis7.5 and we are seeing several errors reported from our global error handler saying that "Request Timed Out". I matched up one to the IIS log file and see the request took 135116 (presumably milliseconds) had an sc-status of 401 an sc-sub0status of 0 and an sc-win32-status of 64.

2 requests failed in these way but lots of surrounding requests (1979 successful requests vs 2 fails) for the same user went through perfectly fine- with the same cs-username which makes a 401 seem a little odd.

The target of the requests is an ASP.Net web service's web method called by the .net client library- it's called a lot of times per user (3 times per second) to keep a page updated.

We're getting some users reportng seeing a freezing effect and I think this may be the cause, any ideas?

Peter

From serverfault TLBH

• Have you looked at the web service's logs itself, to see if that site has some failed requests? It sounds like you put a lot of demands on it, so if it can't handle the simultaneous requests properly, some of the requests get locked or backed up. It's not too unusual for a single request to lock while the requests before and after it continue to work.

  If you can gain access to the logs of the web service itself, I would start digging into that.

  TLBH : Sorry, it wasn't clear in the original post- the web service is part of the web site and is called by the Javascript client library so the log includes the page requests plus those for the web service.

  TLBH : It's the web service requests that are seeing the 401 status (sorry for double post I didnt realise enter would cause a post- was aiming for a new line..)

  Scott Forsyth - MVP : Check out Failed Request Tracing. You can enable it to only log for the long running requests so it won't be too noisy. Once you get a dump, you'll know where it's hanging in the web service call.
  From Scott Forsyth - MVP