iis using cifs share (unc) really slow! here’s the solution.

I just spent the whole weekend waging war with my IIS box (2003 server). After switching the files from a local drive to a netapp share (cifs), the speed of my site slowed to a crawl.
The pages would still appear – but the pace was incredibly slow.
What’s more, the ISAPI REWRITE extension was no longer working, even though the httpd.ini file was in the web root – as it had been before, but for some reason the rewrite extension could not see the file.

So, I hoped that my usual strategy would yield the solution to the problem. The right combination of keywords usually finds a forum entry with the same problem and a corresponding solution. This time however, no such luck. A good hint did come from the helicon tech forum (the makers of ISAPI rewrite).

The solution was to change the application pool identity (user).
The network service user – the default for an application pool – did not have proper access to the share (although it did have some access – probably after x timeouts). The new user (specifically created for the cifs share) solved the problem and IIS is humming again. I had to add some group memberships to this user to make it work.
Hope this helps someone in the same situation.