We're running a Windows Server 2003 SP1 file server with 4 Windows Server
2003 SP1 IIS6 web servers in a web farm grabbing files over the network using
pass through auth and virtual dirs mapped to UNC paths. We setup file
dependencies there to files in 125 directories (looking in Reflector it
appears that the file change stuff adds notifications at the directory level
and then looks at the files inside to see if one you're monitoring was hit
and notifies the framework). In the early mornings during low traffic and
our 5AM IIS app recycle, file dependencies work fine. Later during the day
the dependencies no longer work. The file can be changed by a web server or
even deleted by hand directly on the file server and the web servers still
think it hasn't changed (confirmed using reflection on our cached object).
Even 10 minutes later. Nothing strange in IIS or file server event logs or
app error logging.

Are we hitting some limit in the monitoring system if we can have
potentially up to 1,000 dirs monitored? Any settings in the registry or
otherwise that may help? It seems like a bug somewhere in the framework or a
limitation of the file change monitor API itself.

We tried increasing MaxCmds / MaxMpxCt as per another article and that
didn't make any difference.