In Oracle Enterprise Manager Grid Control, the Agents, Hosts, Listeners were all displaying correctly with status of ‘up’.
But the databases reported status of “Metric Collection Error”.
When I tried to configure a database, the configure database page displayed either one of these errors at top of page:
oracle.sysman.emSDK.emd.comm.CommException: java.io.IOException: Cannot establish proxy connection: 503 Service Unavailable oracle.sysman.emSDK.emd.comm.CommException: java.net.NoRouteToHostException: No route to host
Problem was agent server firewall settings blocking ports.
Fix for me was:
1) on agent server as oracle
cd /software/oracle/product/agent10g/bin ./emctl status agent
Look for “Agent URL” in the output of that command, in my case that was
2) On Grid Control server as oracle, paste that line into a wget command at the command prompt:
wget --no-check-certificate https://myagentserver.mydomain:3872/emd/main
That failed with: “failed: No route to host”, fix was as below:
3) On agent server again – as root
Make backup copy before changing settings:
cd /etc/sysconfig cp -p iptables iptables.backup
Add a new line for port 3872 by copying one of the existing lines, e.g.:
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 3872 -j ACCEPT
service iptables restart
This worked for me with Oracle Enterprise Manager Grid Control and Agent both version 10.2.0.5 and both on 32 bit linux.