How to coordinate the clock when dual-booting with Windows
kogorman at gmail.com
Mon Dec 11 23:35:53 UTC 2017
On Mon, Dec 11, 2017 at 2:48 PM, Kevin O'Gorman <kogorman at gmail.com> wrote:
> On Mon, Dec 11, 2017 at 1:07 PM, Drew Einhorn <drew.einhorn at gmail.com>
>> 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
>> #define QUESTION ((bb) || (!bb)) /* Shakespeare */
>> Please consider the environment before printing this email.
>> 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.
> I reorganized this reply. Please bottom-post on the list.
> What you say sounds good, but it's a bit confusing to me. Both Windows
> and Linux are NTP-capable, so when you write "NTP is ...." you don't say
> which one you mean. But I take it you're writing about Linux NTP, and what
> you wrote agrees with what I think I knew about Linux. I am not aware of a
> way to configure Windows to do what Linux does, but there's been some talk
> about making Linux do what Windows does instead. I thought I had done it
> but it didn't work, and now I have a situation I don't understand at all.
> Follow along with me....
> I'm running Linux and Linux thinks it's 2 PM on Dec 11 PST. Which it is.
> I reboot and enter BIOS setup. BIOS thinks it's 2 PM on Dec 11, which it
> still is in this time zone but AFAIK BIOS has no concept of time zones.
> Maybe my fix worked and linux is storing local time. But wait, let's check.
> I boot into Windows. Windows thinks it's 6 AM on Dec 11, which is 8 hours
> off. I didn't think Windows could do that, as I wrote above.
> So I fix it. Windows now thinks it's 2 PM on Dec 11. I reboot.
> In BIOS, the time is 22:xx (10 PM). off by 8 hours. So Windows changed
> the BIOS time either when I changed the time or when it shut down, or both,
> and set it to UTC based on Windows' knowledge that we're in the UTC-8:00
> Linux comes up and thinks it's 2 PM on Dec 11 PST. Which it is. But this
> is weird. I was expecting it to accept the BIOS time of 10 PM as being
> local time.
> On a hunch, I ran ntpdate, and here's a new piece of the puzzle:
> 11 Dec 14:37:01 ntpdate: no servers can be used, exiting
> So now I think I should be configuring NTP.
> /etc/ntp.conf contains a few lines that look like NTP servers. They must
> have come with the distro:
> # Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
> # on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
> # more information.
> pool 0.ubuntu.pool.ntp.org iburst
> pool 1.ubuntu.pool.ntp.org iburst
> pool 2.ubuntu.pool.ntp.org iburst
> pool 3.ubuntu.pool.ntp.org iburst
> # Use Ubuntu's ntp server as a fallback.
> pool ntp.ubuntu.com
> So why are no servers usable? Is it possible my router is blocking NTP?
> Is it possible the standard config file is bad? This is Ubuntu 16.04.3.
> Clues, anyone?
> Hmm. It's not quite as bad as i though, but it's still every bit as
confusing. Reaching back in my memory I came up with:
$ ntpq -p
remote refid st t when poll reach delay offset
0.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000
1.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000
2.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000
3.ubuntu.pool.n .POOL. 16 p - 64 0 0.000 0.000
ntp.ubuntu.com .POOL. 16 p - 64 0 0.000 0.000
-18.104.22.168 22.214.171.124 2 u 693 1024 377 19.169 -0.267
*ntp.your.org .CDMA. 1 u 118 1024 377 73.945 1.636
+chl.la 127.67.113.92 2 u 1336 1024 376 22.897 3.010
+time.tritn.com 126.96.36.199 3 u 158 1024 377 21.207 5.454
-pacific.latt.ne 188.8.131.52 3 u 923 1024 377 11.997 1.665
So NTP is working okay (although the ubuntu pool may not be,) but ntpdate
is not. I wonder why?
#define QUESTION ((bb) || (!bb)) /* Shakespeare */
Please consider the environment before printing this email.
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