We have an really weird problem on our web server. A few times each day, all requests are unanswered for 10 to 30 seconds.

The delay looks similar to when a page is compiled (on first load). However, when the problem occurs it looks like all users of all applications/pages (classic asp, html, asp.net, ftp) are affected.

Server info:
Win2k Server SP4, running iis 5.0 with .NET framework 1.1
2 x hyperthreaded XEON 2.4 GHz CPUs

Some things to note:
- When the blockage occurs, the CPU is typically at about 1-10 %, and memory usage is between 100-500mb
- Nothing in the event log
- There's no obvious pattern in the times that the lag occurs

Here's some of the things we've identified that might be causing the problem (some we have been able to test, others not).

---> Looking at when the lag occurs (from the IIS logs) and looking for a way to generate the lag (still have not found a way)
---> Scheduled tasks on the server
---> Sync blocks used in application code
---> Virus scanner / backup script could be accessing a machine.config file
---> Problems with using Microsoft Access with web apps
---> .NET framework / trust levels
---> .NET framework / using too much client script
---> The problem might be caused by application errors
---> The problem might be caused by SMTP
---> The problem might be caused by Oracle client / other applications running on the server
---> The problem might be caused by a large number of file updates.
---> The problem might be caused by IIS timeout settings
---> .NET framework hot fixes might need to be applied
---> The problem might be caused by applications storing too much info in sessions
---> The problem might be caused by DSView (remote access software)
---> .NET framework settings (machine.config / process model settings)
---> Idea: Isolating applications (all applications currently run in the same worker process)
---> The problem might be related to firewall settings

Thanks in advance!
Billy :eek:

commented: Good post! Nuff Said! +36

I don't have the answer Billy, but I would sure like to know that as well. I have the same issue with my W2k Web Server. For whatever reason right in the middle of a page off the server it will lag, and sometimes give a 404 reponse to a link, requiring a refresh? Hmm....

I will be watching replies here as well!

Just received some feedback about this (below) ... Will let you know how this goes.

Some notes
- the lag always seems to happen at the beginning of a request (not in the middle as you mentioned)
- we've looked into this issue for months now. most of the time spent has been looking for possible application causes.
- I think we've had 404 errors. we've definately got some .net 'request timed out' errors and weird viewstate/session errors that we think could be related to this problem.


What about non-IIS network issues...Like Terminal Services? (Preferably through the firewall over VPN.) What does the network activity on the NICs look like at the time of the slowdowns?

> Idea: Isolating applications (all applications currently run in the same worker process)

I don't know if that's going to help you...Since you said that it's even effecting FTP calls. That's a different service altogether.

Since both web and and ftp are definitely being effected, and the server utilization is very low, My first thought is that I'd want to concentrate on looking for network issues, from the server's network interfaces on out.