Oracle Enterprise Manager Installation First I install oracle 11g database with this configuration

Step 2 of 9

I selected Create and configure a database

Step 3 of 9

I selected Desktop Class

Step 4 of 8

Global database name: Blitz

Administrative password: Pass1234

After that it gives me this information

Global Database Name: Bliz

System Identified(SID): Blitz

Server Parameter File name: C:\app\annie\product\11.2.0\dbhome_3\database\spfileBlitz.ora

The Database Control URL is https://localhost:5501/em

Management Repository has been placed in secure mode wherein Enterprise Manager data will be encrypted.
The encryption key has been placed in the file: C:/app/annie/product/11.2.0/dbhome_3/localhost_Blitz/sysman/config/emkey.ora.
Please ensure this file is backed up as the encrypted data will become unusable if this file is lost.

Then configure this:

Username - Password

SYS      - Pass1234

SYSTEM   - Pass1234




Then I try to install Oracle Enterprise Manager 12c

First in Command Prompt I enter the following command to get the host name:

sqlplus / as sysdba

select host_name from v$instance

that gives me PC1

Then in Step 6 of 9 of Enterprise Manager Installation

I provide the following for Database Connection Details

Database Host Name: PC1

Port: 1523

Serivice/SID: Blitz

SYS Password: Pass1234

But I got this error

There was a problem connecting to the database on the host and port specified. Check to make sure the host is up or that the database listener is running on that host.

So I tried tried  to changed the Database Host Name to localhost

But I got this error

Enterprise Manager Database Control schema exists in the database. To proceed with the installation of Enterprise Manager Cloud Control, you must deconfigure the same by running the following command:

To deconfigure Database Control for a single instance database, do the following command on database host:
 (a) Set the environment variable &lt;ORACLE_HOME&gt; to the database home.(b) Run the following command:
&lt;Database ORACLE HOME&gt;/bin/emca -deconfig dbcontrol db -repos drop -SYS_PWD &lt;sys password&gt; -SYSMAN_PWD &lt;sysman password&gt;

To deconfigure Database Control for an Real Application Clusters (RAC) database, do the following command on database host:
(a) Set the environment variable &lt;ORACLE_HOME&gt; to the database home.(b) Run the following command:
&lt;Database ORACLE HOME&gt;/bin/emca -deconfig dbcontrol db -repos drop -cluster -SYS_PWD &lt;sys password&gt; -SYSMAN_PWD &lt;sysman password&gt;

NOTE: If the existing database is on different host, then install Oracle Management Agent on the database host, to monitor the database.

So in Command Prompt I enter this command:

set ORACLE_HOME=C:\app\annie\product\11.2.0\dbhome_3

C:\app\annie\product\11.2.0\dbhome_3\bin\emca -deconfig dbcontrol db -repos drop -cluster -SYS_PWD Pass123 -SYSMAN_PWD Pass123

Then it ask me for the details so I input the details.

Database Unique Name: Blitz

Service Name: Blitz

Listner port number: 1523

Listener Home_Oracle: C:\app\annie\product\11.2.0\dbhome_3

But I go this error:





And I'm now stack up with this. Please Help.
Why do you use the    -cluster - option ? 
Is you database repository part of a cluster ? 

Make sure first that you can connect to the database using the tns names.

Example : 

sqlplus system/password@'tns_identified'


Then to deconfig you em repo :
Try using this syntax :

 emca -deconfig dbcontrol db -repos drop -SYS_PWD oracle -SYSMAN_PWD oracle


For some nice articles on how you can prepare you Oracle Enterprise Grid Control Monitoring environment check the link