10G中更改IP地址或者机器名之后要重新配置EM资料库，不然启动dbconsole会失败。（dbca恢复方式建立的数据库会存在sysman用户和某些角色）

重建的步骤如下

1、 drop configuration files and repository run :

emca -deconfig dbcontrol  db -repos drop

2、 Logon SQLPLUS as user SYS or SYSTEM, and drop the sysman account and mangement objects:

a. drop user sysman cascade;
b. drop role MGMT_USER;
c. drop user MGMT_VIEW cascade;
d. drop public synonym MGMT_TARGET_BLACKOUTS;
e. drop public synonym SETEMVIEWUSERCONTEXT;  

 3、Create configuration files and repository run

emca -config dbcontrol db - repos create