We're running a Win 2008 R2 server with IIS 7.5 for serving image files.
It's only used for static content, and file caching has been set up to cache files for 10 minutes.
However the IIS frequently completely flushes the cache (seen by using Perfmon)
It's not application pool recycling, it's not because the TTL has expired, so now I'm at a loss :-(
I've included a screenshot of the perfmon graph where you can clearly see the issue.
Is there anywhere I can see WHY it's doing these flushes ?
(Note: I'm aware I could maybe detect it by attaching a debugger to the process, but that's not an option because it's a production server, and it cannot handle the slowdown a debugger would cause)