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Re: System time 1 hr ahead of real time

2009/4/6 Matthew Saltzman <mjs clemson edu>:
> On Mon, 2009-04-06 at 09:56 -0700, Kam Leo wrote:
>> On Mon, Apr 6, 2009 at 9:17 AM, suvayu ali <fatkasuvayu+linux gmail com> wrote:
>> >
>> > I have a strong hunch booting to XP after the DST change caused this
>> > mismatch. What is the recommended way of maintaining the system time
>> > for dual boot machines?
>> When you use a dual/multi-boot system you need to disable one or more
>> of your systems from automatically updating for daylight savings. This
>> goes whether you are booting multiple versions of Windows or a mixture
>> of Windows and Linux.
> Linux in UTC will always show the correct time (as long as the hardware
> clock is correct UTC), whether on or off at the transition.
> Linux in local time will *not* make adjustments for DST if it is not
> running when the transition occurs, but it will adjust if it is running
> at that time.
> Windows will adjust if it is running or the first time it is turned on
> after the change, no matter what.
> So you can see that there are various kinds of trouble you can get into
> if you try to use local time on a dual-boot machine, depending on which,
> if any, system is running at the transition time.
> I don't use Windows that much, so I keep the hardware clock in UTC,
> Linux running ntpd, Windows in time zone GMT with DST adjustments turned
> off (which has to be done for all Windows users separately).  Then the
> machine shows the correct local time in Linux, but it shows UTC in
> Windows.
> I've heard that there is a Windows registry entry that allows one to
> keep the hardware clock in UTC on Windows, but I've also heard that it
> can break things.
>> The other issue is that you need to patch your Windows software.
>> Daylight savings began last month.
> The other thing that makes this hard is that DST starts on different
> dates in different countries, and countries keep changing things...
> --
>                Matthew Saltzman

Thanks Matthew for this clear explanation. I am going to set the
hardware clock to UTC and set Windows to use UTC without DST
corrections to avoid further confusion. This seems like the most
sure-shot way to tackle the problem.

Thanks to all who replied. :)


Open source is the future. It sets us free.

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