How to coordinate the clock when dual-booting with Windows

[Drew Einhorn]

NTP is probably assuming system clock is UTC and correcting based on your time zone settings. This way ntp can assume all clocks are UTC and not have figure out all the relevant time zone corrections.

Does this make sense for your time zone? 

Remote users can set their time zone environment variables for their local time zone. Things work out nicely on Unix or Linux based systems.

I don't know If there is a right way to configure Windows so it knows the hardware clock is UTC and the user time zone is different. If not, you have different issues depending on whether the hardware clock is UTC or local time. You may have to decide which issues are the bigger problem.

Windows may screw things up for spring and fall daylight savings adjustments, if Windows thinks the hardware is on local time when it's really on UTC. 

If the latest updates are not installed, your systems may change to or from daylight savings on the wrong weekend. This can be an issue for all operating systems. 

My daughter's alarm clock switched itself from daylight savings time to standard time on the wrong weekend this year. And, there is no way to update the rules for when to change.



On December 11, 2017, at 12:47 PM, Kevin O'Gorman <kogorman at gmail.com> wrote:

On Sun, Dec 10, 2017 at 11:23 PM, Grizzly via ubuntu-users <ubuntu-users at lists.ubuntu.com> wrote:

10 December 2017  at 20:41, Kevin O'Gorman wrote:
Re: How to coordinate the clock whe (at least in part)

>On Sun, Dec 10, 2017 at 12:59 PM, Grizzly via ubuntu-users <
>ubuntu-users at lists.ubuntu.com> wrote:
>
>> 10 December 2017  at 15:52, Colin Law wrote:
>> Re: How to coordinate the clock whe (at least in part)
>>
>> >On 10 December 2017 at 15:45, Liam Proven <lproven at gmail.com> wrote:
>> >
>> >> On 10 December 2017 at 10:42, Colin Law <clanlaw at gmail.com> wrote:
>> >> >
>> >> > The clock is not normally an issue when dual booting.
>> >>
>> >> It bally well is for me!
>> >>
>> >> E.g. if it's set to local time, both OSes move the system clock
>> >> forward or backwards when daylight savings times begins or ends,
>> >> resulting in a 2h discrepancy.
>> >>
>> >> My solution: minimize use of Windows. I boot it a couple of times a
>> >> year, if that, normally.
>> >>
>> >
>> >Interesting, I have never seen that. I assumed the system clock was in
>> UTC,
>> >and so would not change with DST.  You may be right about that though, I
>> >have no evidence either way. However I would have thought it would re-sync
>> >the next time ntpdate or whatever it is that does the auto timesync ran.

>> Its on a tab in date/time that not many people visit, default is off

>> That's what I was hoping, but I cannot find anything about NTP in my
>Windows 10.

Must admit I was unsure if the same controls carry forward to later windoz, (I
stopped at Win7) it looks like they do

https://www.isunshare.com/windows-10/2-ways-to-change-date-and-time-on-windows-1
0.html

only difference appears that you only see the internet time when you click
"Change date time"

here it (now) has a number of possible time server, IIRC it came with only two
(unreliable), the rest I added later

there is a reg entry

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DateTime\Servers]
@="3"
"1"="time.windows.com"
"2"="129.6.15.29"
"3"="0.uk.pool.ntp.org"
"4"="1.uk.pool.ntp.org"
"6"="ntp2b.mcc.ac.uk"
"5"="ntp2a.mcc.ac.uk"
"7"="ntp2c.mcc.ac.uk"
"8"="ntp2d.mcc.ac.uk"
"9"="ntp.exnet.com"

the chosen NTP server does propagate to other Reg entries

but you can manually add direct in the dialogue if you don't want to delve in
Registry



This is interesting, but I'm uncertain how to use it.  I found the list of servers in the registry.  I didn't put them there, but there are 5, and number 5 appears as the default.  It is time-b.nist.gov which I sure hope is not unreliable.  However, I still get Windows showing the time off by 8 hours when it boots up, and I'm supposing that's because it is using the time in the BIOS DRAM, but I'm unsure because as near as I can tell the BIOS is set to local time; at least that's what I see when I'm in BIOS setup.  Frankly I'm all confused.


It would be nice if Windows would use nist.gov and apply the timezone, ignoring BIOS completely.


-- 

Kevin O'Gorman

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