Where does the time of IFS stored files come from ?

470 pts.
Tags:
AS/400
CPYTOIMPF
IFS
QTime
Summer Time
Since we have shifted to summer time, and adapted the Qtime value of the ISeries (V5R4 Model 525), the files created by ISeries native applications and moved by this applications to IFS automaticaly using CPYTOIMPF present a bad creation/modification time. The time is one hour later. I don't find the explanation or the solution for that. I've checked moving a file from my C drive to IFS. The problem does not occur.
ASKED: April 11, 2008  7:25 AM
UPDATED: April 21, 2008  8:52 AM

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Hi,

Have you IPL’ed since you shifted over to summer time? Maybe there’s a job still running which has winter time as an attribute?

Regards,

Martin Gilbert.

——————————————————————————

My first question would be “How did you implement the summer time QTIME shift?”.

IFS times are internally stored as a UTC value and being off by an hour suggests that the internal UTC based clock is also off by an hour. This could be caused by someone using CHGSYSVAL QTIME to alter QTIME by an hour in order to reflect daylight saving time, or someone using the time adjustment capability of the system to adjust local time by an hour. The correct way to implement summer time is to have the correct time zone (correct in terms of DST rules and UTC offset) specified in the system value QTIMZON — in which case summer time start and end is automatic.

I seem to recall that IFS does, for historical reasons, maintain time related information in a cache which may not be immediately updated. But the update would be within an hour (worst case) of the summer time transition.

Bruce Vining
<a href=”http://www.brucevining.com/”>http://www.brucevining.com/</a>
Providing integrated solutions to the System i user community

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  • TSCHMITZ
    Hi Martin and Bruce, the machines has been IPL'ed at least 3 times after Time shift. I made the change using WRKSYSVAL QTIME modifying the time manually. We here work with GMT+ 1 time and the QTIMZON is set as : Change System Value System value . . . . . : QTIMZON Description . . . . . : Time zone Type choice, press Enter. Time zone . . . . . . QP0100UTCS Name Associated settings: Offset . . . . . : +01:00 Full name . . . : UTC+01:00 Standard Time Abbreviated name : UTC+01:00S All the parms sound to me ok, but the problem goes on now. The IFS created documents using I5 software are dated on hour to joung. (Time not yet elapsed). I perhaps did the mistake changing the time manually using WRKSYSVAL QTIME, but QTIME is now correct. How can i fix that now ? Thierry Schmitz.
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  • bvining
    Your error was indeed in manually changing QTIME. The time zone QP0100UTCS is defined as not observing summer time and so by changing QTIME by an hour with no summer time adjustment being taken into consideration you have inadvertently also changed the internal UTC time of the system. Do a WRKTIMZON TIMZONE(QP01*) and you will find 5 time zone definitions that are provided with i5/OS. Look at the time zone definitions and find the one that matches your local summer time rules. QP0100CET4 for instance is used if summer time starts at 2:00 local time on the last Sunday in March and ends at 3:00 local time the last Sunday in October. QP0100CET3, on the other hand, defines summer time as starting at 2:00 local time on the last Monday in March and ending at 2:00 local time the last Sunday in September. CHGSYSVAL QTIMZON to the appropriate time zone. This will cause QTIME to then shift by an hour as summer time is now being used. CHGSYSVAL QTIME to the correct local time (this will cause an update to the internal UTC clock) and everything should be OK (after waiting a few minutes for the IFS cache to be updated). Come the end of summer time, do not do anything -- the system will automatically adjust QTIME (your local system time) to reflect the end of summer time. I hope this helps, Bruce Vining http://www.brucevining.com/ Providing integrated solutions for the System i user community
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  • Lovemyi
    If you changed the time in the system value and you are on V5R3 or higher then the QTIMZON value did not autmatically change when you thought it should. You should not have to change the time as the QTIMZON value knows when to change the time. If you do a WRKTIMZON command, you will see the details of the QP0100UTCS and when it will go to daylight savings time and back to standard time. You need to check it right away as the time will change ahead an hour when you least expect it if you do not. Then to fix it, roll the QTIME back one hour just prior to it automatically kicking in so it will spring ahead again. You may also want to use a different value other than QP0100UTCS as you look at the list to find one that will change on the appropriate weekends. Good hunting.
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  • Rickmcd
    Do a Wrksysval QUTCOFFSET if you are in the US it should be -04:00 to - 08:00 depending on time zone and DST.
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  • TSCHMITZ
    Thanks to all. I'll try to fix that Sunday before IPL.
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  • bvining
    If you are doing an IPL Sunday and can wait until then to correct the IFS times then you might be interested in Setting the time zone during an attended IPL. Make sure you have previously identified the correct time zone to specify and then set the appropriate local time and time zone name during the IPL. Bruce Vining http://www.brucevining.com/ Providing integrated solutions for the System i user community
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  • TSCHMITZ
    This has been fixed by : CHGSYSVAL QTIMZON to QP0100CET4. And the shift of hour that this command has created was corrected by CHGSYSVAL QTIME to the correct local time. I made IPL and everything was ok. Regards. TSchmitz
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