Why does Web Farm Framework keep marking the WFE’s as Unhealthy

iis-7web-farmwindows-server-2008

Every few hours, Web Farm Framework takes my farm down with a 502 error and the 2 WFE's in the farm are marked as Unhealthy.

I have no Validation URL set up in Health Monitoring, and everything is fine for another few hours if I manually 'Make Server Available', then same thing.

WFF is load balancing an ASP.NET application. How can I find out why they're getting marked as unhealthy, or just disable the health detection so the WFE's will only go offline in a deployment error?

EDIT: This is the latest Web Farm Framework on IIS.net as of yesterday.

Best Answer

I think I found the answer. I you recycle the ARR application pool you get the 502.4 error when trying to access the secondary servers through the WFF controller (which is the http load balancer). I set the Idle time-out to 0 minutes to disable application pool recycling.

From http://forums.iis.net/t/1158399.aspx

"Functionally speaking, this value has no impact on how ARR works. The idle time-out is designed to bring down the worker process in order to free up more memory. (The default value is 20 min. So for example, if you have multiple sites/applications in multiple applications pools, and if there has been no activity on one of them, IIS will bring down the worker process - so that other processes/etc can consume the resource on the machine.)

Since ARR is proxying the all requests to the content/application servers behind it, we recommend that the worker process is running all the time. (That said, if there is a constant flow traffic, then the worker process would be running all the time, irrespective of this value. ie. It won't be idle for 20 min.)"

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