Suddenly after reboot of server is started to see below errors in logs and website was down.
Service Temporarily Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.
[Wed Feb 01 13:29:45 2012] [error] proxy: AJP: disabled connection for (127.0.0.1) [Wed Feb 01 13:30:46 2012] [error] (111)Connection refused: proxy: AJP: attempt to connect to 127.0.0.1:8009 (127.0.0.1) failed [Wed Feb 01 13:30:46 2012] [error] ap_proxy_connect_backend disabling worker for (127.0.0.1) [Wed Feb 01 13:30:46 2012] [error] proxy: AJP: failed to make connection to backend: 127.0.0.1 [Wed Feb 01 13:30:55 2012] [error] proxy: AJP: disabled connection for (127.0.0.1)
Cause of this was failure to create file requested by application logic. For some reason I restarted tomcat which did not help but after restart of apache it started to work like it was working for some time before. See also setting up apache and tomcat proxy.