DST Safe Kernel

Use

As of SAP Web AS 6.40, you can use the Daylight Saving Time (DST) Safe Kernel to avoid potential problems due to the switch from summer to winter time. This switch can cause problems because the clocks are set back by one hour, which means that an hour is repeated. For programs that use timestamps, this can cause the following problems:

·        Timestamps from different real times can have the same value

·        The timestamps do not necessarily reflect the sequence in which system events really occurred

Programs that use timestamps based on Coordinated Universal Time (UTC) are not affected by this problem.

Since not all timestamps in the SAP system are based on UTC, SAP has up till now recommended that you bring down the system, to avoid the problems described above.

Features

The new solution with SAP Web AS 6.40 is that time during the “repeated hour” runs at half the usual speed. This means that the system can rely on timestamps in the correct sequence without duplicates, even if it is not using UTC.

The result is that – even if you are using local time – you do not normally need to bring down your SAP system during the switch from summer to winter time.

If you have special requirements and anticipate problems with how this new function works, we recommend that you continue to bring down your systems during the switch from summer to winter time.