I have 2 web farm configurations, one with 2 member servers and one with 3 member servers. I have health monitoring set up on both farms and the monitoring tool reports all servers as being healthy. However after a while all the servers are marked as being "Unavailable" and "Healthy" in the "Monitoring and Management" screen (in the "Servers" screen they are all listed with "Yes" in the "Ready for Load Balancing" column).
Viewing the event log on both the web farm controller or any of farm servers doesn't reveal anything interesting. there are no warnings or errors in the period where the servers became unavailable. There are a couple of informational events about the worker process getting shut down due to inactivity but I don't hope this is the cause since that would mean that the farms will die during the night when the load is low.
Am I missing something?
EDIT: Btw, I think its very odd that the application pool shuts down on the servers since the health monitoring system is polling an aspx page on each server. Shouldn't that keep them going?
EDIT2: Now I've also experienced this problem with the RTW version of Web Farm Framework 2.
Check the system and platform requirements for the Web Farm Framework 2.0 for IIS. http://learn.iis.net/page.aspx/913/system-and-platform-requirements-for-the-web-farm-framework-20-for-iis-7/ I had the same problem because the primary server was running Windows Server 2008 and secondary servers were running Windows Server 2008 R2 and this is not supported.