I got a question from a client about Oracle Data guard timezones requirements. They asked if the timezones on the Primary and Standby servers need to be the same or not? The first thing that came to mind is that from my experience it simply does not matter at all. For example if your Primary Database server is in Chicago(Central time) and your Standby Database server is in New York(Eastern time) then you should not have any issues with log shipping replication.
I was talking to an Oracle consultant on the topic today and he pointed out that the Oracle documentation actual does recommend that BOTH Primary and Standby Database servers should consider having the same timezone. This was something I learned new about Data guard.
Check out the verbiage from the 12c documentation, Data guard Concepts and Administration guide. That came as
https://docs.oracle.com/database/121/SBYDB/standby.htm#SBYDB4717
"Because some applications that perform updates involving time-based data cannot handle data entered from multiple time zones, consider setting the time zone for the primary and remote standby systems to be the same to ensure the chronological ordering of records is maintained after a role transition."
Based on this information it perhaps would be a good idea to consider using one standard timezone for database servers in a Data guard configuration such as the GMT or the UTC+0 timezone. Keep in mind before considering this standard that you would need to check if your specific application cannot handle data entered from multiple time zones, if this is the case then consider using the same timezone for your Database servers in the Data guard configuration. One another option workaround would be to ensure the timezone data is recorded from the application as the data is recorded into the database, this configuration would allow different time zones for the database servers in a data guard configuration and should not present any issues after a role transition.
