6 Replies Latest reply: Feb 23, 2012 10:35 AM by Denis Gomes RSS

Daylight saving time

Denis Gomes
Currently Being Moderated

Hi gurus,

  I'm in a question about daylight saving time. Do we need to shutdown the database and the instance for daylight saving time?

 

For instance:

23:55h - Shutdown Oracle and SAP

Wait for an hour.

00:10h  - Startup Oracle and SAP

 

I know that AIX change the time automatically, but Oracle I don't know.

 

Environment:

SAP ECC 6.0 Kernel 700

Oracle 10.2.0.4

Aix 6.1

 

Thanks for your help

Denis

Brazil

  • Re: Daylight saving time
    Deepak Kori
    Currently Being Moderated

    Hi,

     

    The DB table picks the value from OS and then UTC and other zone calculation is done in DB as per the codes.

     

    The beginning of daylight saving time is normally not a problem as the time will jump from 2:00 to 3:00, so seen from SAP that no problem. You will only have a 1 hour hole, as the system had nothing to do for one hour.

    So there are no settings or so to maintain or change. Just let SAP system run...

    But it is different when switching back to "normal" time, as there you will have the so called double hour, and even as SAP is working on a solution to this, it is still recommended to shut down the SAP system for this period.

    (searching for the term "daylight saving time" in OSS should give you some notes explaining how SAP is handling it)

     

    Regards,

    Deepak Kori

    • Re: Daylight saving time
      Denis Gomes
      Currently Being Moderated

      Hi deepakkori,

        I already researched about this on OSS and i found the Note 592393 - FAQ: Oracle.

       

      Where it says:

       

      21. How does changing the system time affect Oracle (for example, when daylight saving time is switched to standard time, and vice versa)?

      - Internally, Oracle works with System Change Numbers (SCN) and not with real time stamps. Therefore, a system time change does not have any impact on Oracle, which means that - from a database point of view - you do not need to stop Oracle to carry out a time change. However, you should bear the following restrictions in mind:

       

      - If a time interval occurs twice as the result of a time change, the system cannot determine at which of the two identical points of time it should stop when you perform a point-in-time recovery with an end time in the duplicate interval. However, in this scenario, you can carry out the recovery with a target SCN instead of a target time.

      - If you carry out an RMAN backup during a time change, so that the start time of the backup is after the end time, subsequent "list backup" commands may terminate with errors such as ORA-01455 because the RMAN function cannot handle this constellation. You can solve this problem by recreating the control files that contain the backup information.

      - If you do not convert the system time on WINDOWS both on the database server and on the domain controller, the KERBEROS authentication with SQLPLUS or SVRMGRL can fail because the time variance is too large, and the problems described in Notes 614036 and 620540 occur.

      - If you convert the time zone itself, the conversion may affect columns of the type "TIMESTAMP WITH LOCAL TIME ZONE" or " TIMESTAMP WITH TIME ZONE". These columns are not used in the SAP environment, but may appear in the Oracle ABAP as of Oracle 10g. In this case, you may need to make certain changes when you change the time zone. Refer to Note 1019133 for more information about the "Daylight Saving Time" change in the USA in 2007.

       

       

      Thanks

      Denis

      Brazil

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