我们在使用Oracle时， 可以利用Oracle自带的EM(Enterprise Manager)来更方便的管理我们的数据库。但是有时候我们的em却有时候无法连接，造成这个问题的原因有好多，例如没有正确的配置hostname,或者操作系统的防火墙问题等等。如果出现了问题，我们能否快速的重建em呢？答案是肯定的。我们可以通过Oracle官方文档来参照。但是如果我们对于em里面如此多的配置命令和选项比较头大的时候，你就可以参照此文来重新创建EM。
首先需要设置好环境变量ORACLE_HOSTNAME
export ORACLE_HOSTNAME=testbox.localdomain
然后再执行：
emca -config dbcontrol db -repos recreate
如果这个方法不行的话，你可以手动先drop掉你当前的repo
emca -deconfig dbcontrol db -repos drop
然后再重新创建
emca -config dbcontrol db -repos create
此间过程比较长，大概需要十分钟左右来创建。然后你就可以看到如下提示：
[oracle@testbox j2ee]$ emca -config dbcontrol db -repos create STARTED EMCA at Jul 1, 2014 10:50:24 PM EM Configuration Assistant, Version 11.2.0.3.0 Production Copyright (c) 2003, 2011, Oracle. All rights reserved. Enter the following information: Database SID: erin Listener ORACLE_HOME [ /u01/app/oracle/product/11.2.0/db_1 ]: Password for SYS user: Password for DBSNMP user: Password for SYSMAN user: Email address for notifications (optional): Outgoing Mail (SMTP) server for notifications (optional): ----------------------------------------------------------------- You have specified the following settings Database ORACLE_HOME ................ /u01/app/oracle/product/11.2.0/db_1 Local hostname ................ testbox.localdomain Listener ORACLE_HOME ................ /u01/app/oracle/product/11.2.0/db_1 Listener port number ................ 1521 Database SID ................ erin Email address for notifications ............... Outgoing Mail (SMTP) server for notifications ............... ----------------------------------------------------------------- Do you wish to continue? [yes(Y)/no(N)]: yes Jul 1, 2014 10:50:43 PM oracle.sysman.emcp.EMConfig perform INFO: This operation is being logged at /u01/app/oracle/cfgtoollogs/emca/erin/emca_2014_07_01_22_50_24.log. Jul 1, 2014 10:50:44 PM oracle.sysman.emcp.EMReposConfig createRepository INFO: Creating the EM repository (this may take a while) ... Jul 1, 2014 10:55:39 PM oracle.sysman.emcp.EMReposConfig invoke INFO: Repository successfully created Jul 1, 2014 10:55:42 PM oracle.sysman.emcp.EMReposConfig uploadConfigDataToRepository INFO: Uploading configuration data to EM repository (this may take a while) ... Jul 1, 2014 10:57:43 PM oracle.sysman.emcp.EMReposConfig invoke INFO: Uploaded configuration data successfully Jul 1, 2014 10:57:45 PM oracle.sysman.emcp.util.DBControlUtil secureDBConsole INFO: Securing Database Control (this may take a while) ... Jul 1, 2014 10:58:17 PM oracle.sysman.emcp.util.DBControlUtil secureDBConsole INFO: Database Control secured successfully. Jul 1, 2014 10:58:17 PM oracle.sysman.emcp.util.DBControlUtil startOMS INFO: Starting Database Control (this may take a while) ... Jul 1, 2014 10:58:44 PM oracle.sysman.emcp.EMDBPostConfig performConfiguration INFO: Database Control started successfully Jul 1, 2014 10:58:44 PM oracle.sysman.emcp.EMDBPostConfig performConfiguration INFO: >>>>>>>>>>> The Database Control URL is https://testbox.localdomain:5500/em <<<<<<<<<<< Jul 1, 2014 10:58:48 PM oracle.sysman.emcp.EMDBPostConfig invoke WARNING: ************************ WARNING ************************ Management Repository has been placed in secure mode wherein Enterprise Manager data will be encrypted. The encryption key has been placed in the file: /u01/app/oracle/product/11.2.0/db_1/testbox.localdomain_erin/sysman/config/emkey.ora. Ensure this file is backed up as the encrypted data will become unusable if this file is lost. *********************************************************** Enterprise Manager configuration completed successfully FINISHED EMCA at Jul 1, 2014 10:58:48 PM
标注的红色部分就是我们的em的访问地址。
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原文：http://www.cnblogs.com/rosegun/p/3819275.html