EMCA Release 10.1 to 11.1 Puts the Database in Quiesce And No New Connections or Operations Can Be Performed During the DB Control Repository Creation.

EMCA Release 10.1 to 11.1 Puts the Database in Quiesce And No New Connections or Operations Can Be Performed During the DB Control Repository Creation.

When running 'emca -config dbcontrol db -repos recreate' or 'emca -deconfig dbcontrol db -repos drop' to recreate or drop the Enterprise Manager Database Control configuration files and repository the operation hangs and at the same time users are not able to log in to the database.
NOTE : This applicable only for 10g and 11.1 database release.
Starting 11.2.0.1 database release the database is not put into quiesce mode anymore.  However when dropping the repository with emca or repManager for certain 11.2.0.x versions (eg. 11.2.0.2) this warning will be displayed:

WARNING : While repository is dropped the database will be put in quiesce mode.

This warning can be ignored.  The database will NOT be put into quiesce mode for 11.2.0.1 onwards.  This incorrect message which is displayed for 11.2.0.x databases is logged as bug:12861049.  See Note:1356293.1 for further info.

Cause:

The emca command, when recreating or dropping the repository, requires the database to be quiesced.  This means that, temporarily, no operations are possible on the database and new users cannot login.

When the emca command is running, invoking a repository drop or recreate, several SYS objects are locked.

If there are active sessions on the database at the time the quiesce operation will hang pending their completion, during which time no new users will be able to connect.

Therefore it is important to understand that running these commands may/will cause the database to be unavailable during the time that the repository is being dropped and should not be run on a production database unless you are fully aware of the possible impact to database availability and have planned for this eventuality.

Solution:

Note 1. In release 10.2.0.5 this behavior has been modified and EMCA utility displays warning and seeks confirmation for the database to be put in Quiesce mode.
Reference : Internal Enhancement Request Bug 9357925

Note 2. Starting from 11.2.0.1.0 release, the database is NOT put into quiesce mode anymore for repository drop and recreate operation. This means that emca drop and recreate commands can be executed for 11.2.0.1 database without impacting other sessions in the database.
Reference : Internal Bug 6697464
If the same is required for older versions of database, raise an SR with Oracle Support to check if patch can be provided.

For 10.x and 11.1 databases, to implement the solution, please execute the following steps:

Kill the emca command
Connect to the database with SYS account through SQL*Plus

SQL > alter system unquiesce;

Run the emca command at a time when there is low system usage.

Reference metalink Doc ID 375946.1