又出问题了，发现访问EM时提示“Enterprise Manager 无法连接到数据库实例。下面列出了组件的状态”。其实这个问题不对解决，以下是方法。
1、重新配置em
emca -config dbcontrol db
2、按提示操作
STARTED EMCA at Sep 2, 2013 9:49:11 PM
EM Configuration Assistant, Version 10.2.0.1.0 Production
Copyright (c) 2003, 2005, Oracle. All rights reserved.
Enter the following information:
Database SID: tsing (填写数据库的实例名，如果不知道可先登录数据库select instance_name from gv$instance;查询）
Database Control is already configured for the database tsing
You have chosen to configure Database Control for managing the database tsing
This will remove the existing configuration and the default settings and perform a fresh configuration
Do you wish to continue? [yes(Y)/no(N)]: Y
Listener port number: 1521
Password for SYS user:
Password for DBSNMP user: （输入DBSNMP用户密码，如果密码不对可先登录数据库用alter user DBSNMP identified by 密码 account unlock;修改密码）
Password for SYSMAN user: （同上)
Email address for notifications (optional):(回车）
Outgoing Mail (SMTP) server for notifications (optional):（回车）
-----------------------------------------------------------------
You have specified the following settings
Database ORACLE_HOME ................ /ora/oracle/oracle/product/10.2.0/db_1
Database hostname ................ TAIXIN-HR
Listener port number ................ 1521
Database SID ................ tsing
Email address for notifications ...............
Outgoing Mail (SMTP) server for notifications ...............
-----------------------------------------------------------------
Do you wish to continue? [yes(Y)/no(N)]: Y
Sep 2, 2013 9:55:04 PM oracle.sysman.emcp.EMConfig perform
INFO: This operation is being logged at /ora/oracle/oracle/product/10.2.0/db_1/cfgtoollogs/emca/uqn_node1/emca_2013-09-02_09-49-11-PM.log.
Sep 2, 2013 9:55:05 PM oracle.sysman.emcp.util.DBControlUtil stopOMS
INFO: Stopping Database Control (this may take a while) ...
Sep 2, 2013 9:55:15 PM oracle.sysman.emcp.util.DBControlUtil startOMS
INFO: Starting Database Control (this may take a while) ...
Sep 2, 2013 9:56:59 PM oracle.sysman.emcp.EMDBPostConfig performConfiguration
INFO: Database Control started successfully
Sep 2, 2013 9:56:59 PM oracle.sysman.emcp.EMDBPostConfig performConfiguration
INFO: >>>>>>>>>>> The Database Control URL is http://TAIXIN-HR:1158/em <<<<<<<<<<<
Enterprise Manager configuration completed successfully
FINISHED EMCA at Sep 2, 2013 9:56:59 PM
3、重新登录em看是否成功。