Hi All,
We are in the process of migrating a medium traffic (25M + hits/month) site to IIS 8 on Server 2012 64 bit from our existing platform (Server 2003, IIS 6, 32 bit). The app is written in VB .Net using ASP .NET 2.0 and uses a custom 404 redirector to handle extensionless URLs (which doesn't work in integrated pipeline mode).
Our servers are set up as follows:
- Two identical servers, with a hardware load balancer in front of them using sticky sessions
- Dedicated app pool configured to .NET 2 and Classic pipeline mode
- Worker process set to 32 bit (as recommended athttp://www.iis.net/learn/web-hosting/web-server-for-shared-hosting/32-bit-mode-worker-processes)
- Session state set to in-process
The setup works fine in testing and when first put live, but after around 2.5 hrs CPU usage goes to nearly 100% and eventually the servers become unresponsive. Recycling app pools fixes the problem temporarily, but it seems to set off a chain reaction and eventually both servers become unresponsive, IIS manager crashes if attempting to view running requests. When the site does become responsive again it runs very slowly, as is IIS is stil trying to catch up.
I'm at a loss as to what else to try - has anyone else seen this before?
We initially thought it could be the session state (as we had been using the state server) so changed to in-process. This helped a little, as memory usage on the state server was around 1.5 GB but in-process only swelled the worked process by about 100MB; changing the app pools to 32 bit also helped significantly (worker process memory usage fell from 1.4GB to 400MB).
Any thoughts would be really welcome!!
Thanks
Sam