Oracle dbconsole can't start

環境： redhat 5.0 , oracle 10g

OC4J Configuration Issue: $ORACLE_HOME/oc4j/j2ee/OC4J_DBConsole_host_sid not found

emctl start dbconsole fails with the following error:
OC4J Configuration Issue: $ORACLE_HOME/oc4j/j2ee/OC4J_DBConsole_host_sid not found

There are three cases for this issue:

a) ORACLE_HOME variable needed to run emctl is set to the wrong database home. Set the right value and retry the process.
b) Network changes. If the hostname where Database Control was created in the first place is not resolvable anymore startup will fail with above error.
c) Database Control was not configured.

由於主機名變更，使得dbconsole無法啟動。