Daylight saving time in Germany

[Wolfgang Braig]

Hello everybody,

I have a question about the
ending of the daylight saving
time here in Germany. I wonder how SAP and Oracle will react when going back one hour. Where are running
two HP-UX Servers for our
productive R/3 Instance. Do we need to shut down SAP?

Any help is welcome

Regards,

Wolfgang

[Bruno Vidal]

Hi
The SAP recommendation is to shutdown the application. The system don't care because the internal time didn't change (it is only the interpretation of this time that change), but SAP/Oracle use a lot of gettimeofday(), so timestamps inside the databse can produce strange result.

Bye.

[Wolfgang Braig]

Hy,

is it possible to force the
time switching to be for example on friday. There is
file called tztab, in which the moment of changing of the local time is described. Does it make sense to change this file? I really don't need to work on Saturday night.

Bye

[Robert-Jan Goossens]

Hi Wolfgang,

We shutdown the software + databases using cron (oracle+sybase+ingres) ore you make a script refering to the shutdown scripts in /sbin/init.d.

Regards

Robert-Jan.

[Paula J Frazer-Campbell]

Hi

Have a look at man cron.

Paula

[Wolfgang Braig]

Hy,

I'm not very familiar with cron jobs. Can someone tell me how to stop and the start sap in time with a cron. Is the cron referring to UTC or to local time?

Wolfgang

[Robert-Jan Goossens]

Wolfgang,

Locate your shutdown scripts in /sbin/init.d

Make entry in crontab file like.

Sunday 27-10-2002 at 02.30.
30 02 27 10 * /sbin/init.d/oracle stop >> /dev/null 2>&1

Sunday 27-10-2002 at 03.30
30 03 27 10 /sbin/init.d/oracle start >> /dev/null 2>&1


Regards,

Robert-Jan.

[Andrej Vavro]

How many times is going to be 2:30 on Sunday 27th? Will be the stop scipt executed two times?

Andrej

[Stefan Schulz]

Hi,

in this case i would set the shutdown time to 2:59 and the startup to 3:01

This will shutdown the application just befor the timeshift. It will them be shutdown a second time when its 2:59 again. But this doesn't harm as the application is already down.

The gap between shutdown and startup will be 1 hour and 2 minutes. But the importent part is that there will be no duplicate timestamps.

Perhaps the application needs more time for a clean shutdown. Adjust the times to your needs.

Hope this helps

Regards Stefan

[Tony Lowrie]

Hi

You will not have any problem with Oracle as it handles file Datestamps internally and does not rely on the HP-UX Clock.

Dont lose too much sleep. :-)

[Darrell Allen]

No, cron will not run the same entry twice during "fall back" from daylight to standard time.

"man cron" at look at what it says about "Ambigous time":

On the days of daylight savings (summer) time transition (in time zones and countries where daylight savings time applies), cron schedules commands differently from normal.

In the following description, an ambiguous time refers to an hour and minute that occurs twice in the same day because of a daylight savings time transition (usually on a day during the Autumn season). A nonexistent time refers to an hour and minute that does not occur because of a daylight savings time transition (usually on a day during the Spring season). DST-shift refers to the offset that is applied to standard time to result in daylight savings time. This is normally one hour, but can be any combination of hours and minutes up to 23 hours and 59 minutes (see tztab(4)).

When a command is specified to run at an ambiguous time, the command is executed only once at the first occurrence of the ambiguous time.


Darrell