Rapid-Fail Protection disables application pools if they crash multiple times within in a specified time period. This prevents the failing application pool from getting into a continuous loop of crashing and restarting. This protects other application pools running on the server as repeated failures can consume lot of system resources. When rapid-fail protection kicks in it stops the application pool that is repeatedly crashing and your clients will start getting a 503 – Service Unavailable error. An administrator will have to manually enable the application pool again.
You also have to option to configure an executable to run when ever rapid-fail protection is triggered. For example below I have configured the application pool to restart the IIS service using iisreset.exe … the /rebootonerror will reboot the whole server if iisreset.exe for some reason fails to restart the services.
<add name="DefaultAppPool" autoStart="true">
<failure autoShutdownExe="c:\windows\system32\iisreset.exe" autoShutdownParams="/rebootonerror" />
This option is also available on IIS 6.0 but it is not exposed via the IIS manager. You can set is as follows
cscript adsutil.vbs set W3SVC/AppPools/DefaultAppPool/autoshutdownapppoolexe “c:\windows\system32\iisreset.exe”