isapi_rewrite randomly(?) stops working

[irashkin Profile]

This has been an ongoing problem ever since we switched from Windows 2003 (32 bit) to Windows 2008 (64bit). We are running a licensed copy of isapi_rewrite 3.1.0.89, and most of the time it works just fine.

However, periodically (it varies, but averages every couple of days) it stops working. When this happens, the only thing we've found to help is to restart IIS. Now, the issue is somewhat mitigated by the fact that we are running a Varnish server in front of the web server, so that as long as the page gets cached (on a 22 hour ttl) while isapi_rewrite is working, then we're ok, because the page is served fro the Varnish cache and never has to be rewritten. But, once that cache expires we get the 404. We've also mitigated by moving some of our most important rules in to IIS's rewrite module, as isapi_rewite is just not reliable enough.
All the same, this is becoming more and more problematic, and we need help finding a solution.

You will likely ask to see the log files - unfortunately, I can't provide them, as per this thread: ErroLog_not_created-9-383.html.

What I can tell you is that our (primary) site is http://www.storkie.com, and a good example of an url that should rewrite IF isapi_rewrite is functioning is https://www.storkie.com/jobs (I use https to bypass the Varnish server, otherwise, you won't know if you are getting a cached page or a rewritten one). We use Pingdom to constantly check the status (using that very url), and so we know, within a couple of minutes, when the rewrite stopped working each time. I have searched Windows event logs at the times it has gone down, and found nothing. I have also searched our internal error logs from our application, and found nothing. Ditto IIS logs.

Only one thing I see that seems slightly weird - when I look at isapi filters running on IIS, I see both Isapi_rewrite_32 and Isapi_rewrite_x64; now, the site referenced above (www.storkie.com) has 32-bit applications enabled on its app pool, due to some old legacy dlls it is utilizing, so maybe this is related? Or, maybe it is something we did wrong in installing isapi_rewrite? I remember we had some trouble when first setting it up on the (then) new server.

Any ideas?

Thanks,
Ian

[Anton]

Hello, Ian

Thanks for giving such detailed explanation.
I guess the best and the quickest thing we can do to figure out what's wrong is arrange an online meeting.
If it's possible for you, please write suitable time/date and meeting software to [email protected] (with reference to this forum post).

[tidaltides Profile]

Skype or Team Viewer works best with online meeting.