Hello!

We run a web site where we currently have 10 web servers.

We have built a synchronized cache that works like this.

All servers store its own cache and gets the data from the data source. We
always set a absolute expiration date when we add the cache item. Along with
this we add a cache dependency against a file on a server that all webservers
have access to.

When a new post is made and its time to invalidate all the other webservers
cache the webserver just makes an update to the file. In that way all the
webservers have the latest information and this works really good. We have
been using it for several month.

Now suddenly we are occuring some problems. One or two webservers suddenly
stops to invalidate the cache. So its only when someone posts a message from
the webserver that is not working that an update will be made. The problem is
that not even the absolut expiration is working either. And after someone
have removed the cache item and added it again (like all webservers do
(running on same code)), it still wont start to work.

To make it work again we have to make an iisreset.

Then it will work for a couple of days (2-3 days or so).

We have never been able to reproduce this in our development environment. So
my question is, what is my next step in the search of the error?

Any suggestions is apreciated!

Thanks in advance!