Originally posted by: SystemAdmin

OS 5.3L with Oracle 10.2.0.1
We are in the country of Mexico. The government swithed off the daylight saving last SUnday, Oct 28 (a week before US) Since this is a new AIX, installed it before summer, there was no configured the Summer Daylight Saveing, so the time was one hour ahead of local. I went into the SMITTY and set the daylight saving usine the time ID "CST" and offset -1, and restart the server. Although the new time /date is correct, it mismatched my Oracle EM Agent set-up which is in the america/chicago zone, so it stopped function. What is the proper way to set the daylight saving after the dyalight saving was over. There are the System Defined Values and User Input values. Which one I should use? (my other old AIX has the same configuration, but switched correctly and no problem with the Oracle).
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Originally posted by: SystemAdmin

I tried couple times with the System Defined Values setting in the smitty, click on yes for daylight saving and selected the CST6CDT and entered 6 (not -6, strange) in the offset from CUT, restarted machine. Now I got both correct time and the Oracle em agent started. But I am not sure the next sunday, will the normal american switching off wil change the time of OS again?
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Originally posted by: hwyguy

If you a slight test window, change your system's date to 11/6/2007 and see how your clock reacts..
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Originally posted by: SystemAdmin

The Daylight Savings Time settings is basically controlled by the TZ environment variable ($echo $TZ). You can set the start and end times manually if you want, ensuring it'll "do what you want". For it to persist across boots, edit the /etc/environment file and make the changes there.

On my old 5.1 system, I have it set as follows:

$ echo $TZ
PST8PDT,M3.2.0/2:00:00,M11.1.0/2:00:00
$

The first part is obvious, it's setting it to my local time zone (Pacific). The next parts are interesting, they control when DST starts and stops. Mine starts on month 3 (March), week 2, day 0 (2nd Sunday) at 2:00AM and ends on month 11 (November), week 1, day 0 (first Sunday) at 2:00AM.

If I'm not mistaken, this should work on most AIX versions, certainly all AIX5 versions.
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Originally posted by: SystemAdmin

When I typed

1. echo $TZ

CST6CDT6

1. date

Thu Nov 1 17:46:40 CDT 2007
not CST as my prod AIX, although the time is correct.

It was not like yours.
Also when I am in the smitty, using the USer input Values, I saw the smitty displaying the command as
chtz_proc 'CST' '6' 'CDT' '6' ,'M4.1.0' /'1:00:00' ,'M11.1.0' /'1:00:00'

But actually there is no chtz_proc, only chtz, but with very simple manual. So where is the chtz? I am little confused with the setting.
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Originally posted by: SystemAdmin

Right, that makes sense when you consider you're still in daylight savings time (specifically Central Daylight Time). It would change to CST (Central Standard Time) when you return to standard time.


Good question, I "hacked" my /etc/environment file (and rebooted) manually on my machine. But if I understood your question, on my machine I discovered:

$ whereis chtz
chtz: /usr/bin/chtz
$

I would run through 'smitty chtz' to see what it would do, but I don't want to mess around with the settings I currently have on my companywide time server (it's a very old and finicky machine). My suggestion would be to try it out and then check your $TZ and see if it's done what we expect it to do. My guess is it will, but if not you now know where to set this up manually (/etc/environment). The format isn't too bad to figure out, the trick is to know how many Sunday's there are in the month leading up to and including the DST shift. For example, if it's the first Sunday of November, you want 'M11.1.0'. The slash (/) separates this from the time when the shift happens, so if you change time at 1AM (meaning at 1:00AM it's actually 12:00 midnight) you have it (/'1:00:00').

Of course this all may be moot for the moment, since I think we've passed the time you have set for the rollback to happen. But it will be good to know this for next year when you're faced with the same situation all over again.
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