Daylight Saving Time experience for SAP ECC on HANA
During the recent time change in Europe on Oct 29, there’s a bit of a debate among SAP users. Some folks think it’s a good idea to restart their SAP systems to avoid potential problems caused by the time shift, especially for important tasks like BG Jobs and Posting. However, there’s another side to the discussion suggesting that if your system operates in GMT and UTC time zones, maybe a restart isn’t really necessary.
Let me share what happened when our SAP system, running on HANA 2.0 SPS05 with NW 7.40 in the GMTUK time zone, went through the DST change. We decided not to restart, and it turned out fine.
Time Zone – GMTUK (CET -1), (UTC +1)
According to SAP Note 2375952, there’s this parameter called zdate/DSTswitch_contloctime that’s supposed to handle the situation, and it’s automatically turned on since kernel 6.40.
According to parameter description –
When transferring from summer to winter time, an hour takes place twice. The SAP system can only run for this time as a whole or in part under certain conditions. If it is running, this profile parameter specifies how the system time (SY-UDATUM, SY-TUZEIT) behaves. If the parameter is set to ‘off’, the ‘doubled hour’ is also displayed twice. If the parameter is set to ‘on’, the doubled hour is ‘expanded’, so that no doubled times can arise, that is, for example:
•off: 2:00, 2:30, 2:00, 2:30, 3:00.
•on : 2:00, 2:15, 2:30, 2:45, 3:00
Now, this parameter deals with what happens during that tricky hour when we switch from summer to winter time. If set to ‘off,’ the doubled hour appears twice; if set to ‘on,’ it cleverly expands the hour to avoid the doubling effect. The whole point is to slow down time during that double hour, creating a time lag of up to 30 minutes compared to the official time.
You might notice some errors in the work process trace, but don’t worry—the system won’t shut down, and you won’t run into the ZDATE_LARGE_TIME_DIFF dump. After a couple of hours, the system clock smoothly adjusts itself to the new time zone without any hiccups. So, it seems like not hitting the restart button worked out just fine for us!
Now all 2 hours passed, system clock only change itself to 1 hour and adjust accordingly with the new time zone without any double hour issue.
Important Notes to consider –
2375952 – Daylight saving time: Is a restart needed for Winter to Spring change
3015840 – Daylight saving time: best practices
2080216 – Check HANA DB for DST switch
102088 – Daylight saving time changeover; standard time, reduction of downtime