To change the Oracle timezone
Answer: First, see my notes on Oracle timezone. To see your local time zone, enter:
select sessiontimezone from dual;
The time_zone is normally set at database creation time:
create database . . . set time_zone='+00:00';
To change the Oracle timezone for an existing Oracle database, change the time_zone parameter and then bounce the database.
alter database set time_zone = '-05:00'; shutdown immediate startup
For OMS, log into the OMS repository as the SYSMAN user, the above command 'emctl resetTZ agent' tells you exactly what needs to be executed in the repository.
SQL> exec mgmt_target.set_agent_tzrgn('', 'Etc/GMT-6');
SQL> commit;
SQL> emctl start agent -- (or emctl start dbconsole)
Reference:
MOSC: Timestamps & time zones - Frequently Asked Questions Doc ID: Note:340512.1