dual-boot time issue

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
5 messages Options
Reply | Threaded
Open this post in threaded view
|

dual-boot time issue

J.Witvliet

Hi all,

 

It seems I’m bothered by an old issue again, though googling tells me, I am not the only person effected….

 

The general issue arrises when dual-booting:

Ubuntu_18.04 uses UTC, derived from NTP

Windows uses Local Time, derived from hwclock.

 

Normally the two can co-exists together, except, when stopping Ubuntu, System-D writes its time back to the hwclock.

No big deal for Ubuntu (as it will use ntp), but a source of irritation under Windows.

 

I do know several suggestions, like:

a)      Make Windows10 use UTC instead of local time.
This would solve everything once and for all FOR ME, but not achievable for others.

b)      Make Ubuntu_18.04 use local time, with: “timedatectl set-local-rtc 1 --adjust-system-clock”
However, I’m about to switch to Kerberos for several services, so I must use a reliable source for time.

 

It seems that system-d is the culprit, in initiating the writing of the current time back to the bios/hwclock.

Is there anything I can do, to stop system-d causing this inconvenience ?

 

Kind regards, Hans


Dit bericht kan informatie bevatten die niet voor u is bestemd. Indien u niet de geadresseerde bent of dit bericht abusievelijk aan u is toegezonden, wordt u verzocht dat aan de afzender te melden en het bericht te verwijderen. De Staat aanvaardt geen aansprakelijkheid voor schade, van welke aard ook, die verband houdt met risico's verbonden aan het elektronisch verzenden van berichten.

This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. The State accepts no liability for damage of any kind resulting from the risks inherent in the electronic transmission of messages.
--
ubuntu-users mailing list
[hidden email]
Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-users
Reply | Threaded
Open this post in threaded view
|

Re: dual-boot time issue

Robert Heller
At Tue, 12 Jun 2018 11:45:54 +0000 "Ubuntu user technical support,  not for general discussions" <[hidden email]> wrote:

>
> Content-Language: en-US
>
>
> Hi all,
>
> It seems I'm bothered by an old issue again, though googling tells me, I am not the only person effected....
>
> The general issue arrises when dual-booting:
> Ubuntu_18.04 uses UTC, derived from NTP
> Windows uses Local Time, derived from hwclock.
>
> Normally the two can co-exists together, except, when stopping Ubuntu, System-D writes its time back to the hwclock.
> No big deal for Ubuntu (as it will use ntp), but a source of irritation under Windows.
>
> I do know several suggestions, like:
>
> a)      Make Windows10 use UTC instead of local time.
> This would solve everything once and for all FOR ME, but not achievable for others.

This is the *ideal*, network friendly, solution, esp. if Windows10 would also
use ntp.  But M$ is not going to do the "proper" thing...

There is the option of doing away with "dual booting", and instead use VMs.
This way you only have one O/S touching the bare metal (the host O/S) and no
conflicts over what to do with the bare metal. This way everybody do their
normal thing with no problems...

>
>
> b)      Make Ubuntu_18.04 use local time, with: "timedatectl set-local-rtc 1 --adjust-system-clock"
> However, I'm about to switch to Kerberos for several services, so I must use a reliable source for time.

Is is possible to combine this with ntp?

>
> It seems that system-d is the culprit, in initiating the writing of the current time back to the bios/hwclock.
> Is there anything I can do, to stop system-d causing this inconvenience ?

There is *probably* a shutdown service somewhere that controls this.

>
> Kind regards, Hans
>
> Dit bericht kan informatie bevatten die niet voor u is bestemd. Indien u niet de geadresseerde bent of dit bericht abusievelijk aan u is toegezonden, wordt u verzocht dat aan de afzender te melden en het bericht te verwijderen. De Staat aanvaardt geen aansprakelijkheid voor schade, van welke aard ook, die verband houdt met risico's verbonden aan het elektronisch verzenden van berichten.
>
> This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. The State accepts no liability for damage of any kind resulting from the risks inherent in the electronic transmission of messages.
> MIME-Version: 1.0
>

--
Robert Heller             -- 978-544-6933
Deepwoods Software        -- Custom Software Services
http://www.deepsoft.com/  -- Linux Administration Services
[hidden email]       -- Webhosting Services
               

--
ubuntu-users mailing list
[hidden email]
Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-users
Reply | Threaded
Open this post in threaded view
|

Re: dual-boot time issue

Colin Watson
In reply to this post by J.Witvliet
On Tue, Jun 12, 2018 at 11:45:54AM +0000, [hidden email] wrote:

> The general issue arrises when dual-booting:
> Ubuntu_18.04 uses UTC, derived from NTP
> Windows uses Local Time, derived from hwclock.
>
> Normally the two can co-exists together, except, when stopping Ubuntu, System-D writes its time back to the hwclock.
> No big deal for Ubuntu (as it will use ntp), but a source of irritation under Windows.
>
> I do know several suggestions, like:
>
> a)      Make Windows10 use UTC instead of local time.
> This would solve everything once and for all FOR ME, but not achievable for others.
>
>
> b)      Make Ubuntu_18.04 use local time, with: "timedatectl set-local-rtc 1 --adjust-system-clock"
> However, I'm about to switch to Kerberos for several services, so I must use a reliable source for time.

b) seems like the proper fix, if you don't want to (or can't)
reconfigure Windows.  systemd or anything else writing to the hardware
clock isn't the problem in and of itself; it just needs to make sure to
apply the correct offset, and that's what "timedatectl set-local-rtc 1"
does.

I don't see how this is related to using a reliable source for time.
You should probably omit the --adjust-system-clock option, since you
don't need to synchronise the system clock from the hardware clock; but
once you've run that timedatectl command once, the system should be
configured to do the right thing when writing to the hardware clock from
then on.

--
Colin Watson                                       [[hidden email]]

--
ubuntu-users mailing list
[hidden email]
Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-users
Reply | Threaded
Open this post in threaded view
|

RE: dual-boot time issue

J.Witvliet
In reply to this post by J.Witvliet
-----Original Message-----
From: ubuntu-users [mailto:[hidden email]] On Behalf Of Colin Watson
Sent: dinsdag 12 juni 2018 15:02
To: [hidden email]
Subject: Re: dual-boot time issue

On Tue, Jun 12, 2018 at 11:45:54AM +0000, [hidden email] wrote:

> The general issue arrises when dual-booting:
> Ubuntu_18.04 uses UTC, derived from NTP Windows uses Local Time,
> derived from hwclock.
>
> Normally the two can co-exists together, except, when stopping Ubuntu, System-D writes its time back to the hwclock.
> No big deal for Ubuntu (as it will use ntp), but a source of irritation under Windows.
>
> I do know several suggestions, like:
>
> a)      Make Windows10 use UTC instead of local time.
> This would solve everything once and for all FOR ME, but not achievable for others.
>
>
> b)      Make Ubuntu_18.04 use local time, with: "timedatectl set-local-rtc 1 --adjust-system-clock"
> However, I'm about to switch to Kerberos for several services, so I must use a reliable source for time.

b) seems like the proper fix, if you don't want to (or can't) reconfigure Windows.  systemd or anything else writing to the hardware clock isn't the problem in and of itself; it just needs to make sure to apply the correct offset, and that's what "timedatectl set-local-rtc 1"
does.

I don't see how this is related to using a reliable source for time.
You should probably omit the --adjust-system-clock option, since you don't need to synchronise the system clock from the hardware clock; but once you've run that timedatectl command once, the system should be configured to do the right thing when writing to the hardware clock from then on.

=============================================================================
Option a) should be better, but is beyond my reach (especially for other systems)
Option B) seems nice, but when using Kerberos, you need a steady and reliable time source.

For Ubuntu there is no problem, it works well with our own time-source,
But the problem arises when people shuts down and subsequently boots windows (yeah, I know, bad move altogether, but such is life)
So during shutdown I think the system should either:
- Not write to the hwclock at all, or,
- write the converted UTC-2-LTC (to keep the win-users happy)

Up to now, I failed to see a system option to influence this behavior.
(could I mislead the system by using the package: "fake-hwclock", or would I break other parts?)

HtH, Hans

Dit bericht kan informatie bevatten die niet voor u is bestemd. Indien u niet de geadresseerde bent of dit bericht abusievelijk aan u is toegezonden, wordt u verzocht dat aan de afzender te melden en het bericht te verwijderen. De Staat aanvaardt geen aansprakelijkheid voor schade, van welke aard ook, die verband houdt met risico's verbonden aan het elektronisch verzenden van berichten.

This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. The State accepts no liability for damage of any kind resulting from the risks inherent in the electronic transmission of messages.
--
ubuntu-users mailing list
[hidden email]
Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-users
Reply | Threaded
Open this post in threaded view
|

Re: dual-boot time issue

Colin Watson
On Tue, Jun 12, 2018 at 01:34:29PM +0000, [hidden email] wrote:
> Option B) seems nice, but when using Kerberos, you need a steady and
> reliable time source.

As far as I can see, option B doesn't affect the maintenance of the
system clock while your system is running, and therefore it doesn't
impair your ability to have a steady and reliable time source.  It
simply configures the system to use an offset when writing to the
hardware clock at shutdown, and it doesn't stop you using NTP.

As I said in my previous message, you should leave out the
"--adjust-system-clock" option, since you don't want to resynchronise
your system clock from the hardware clock when you make this
configuration change.  That option is mainly intended for use in
environments where you have some reason to believe that the hardware
clock is likely to be more reliable than the system clock, which isn't
your case.

> So during shutdown I think the system should either:
> - Not write to the hwclock at all, or,
> - write the converted UTC-2-LTC (to keep the win-users happy)

"timedatectl set-local-rtc 1" configures the system to do the second of
those.  (Its main technical effect is to write appropriate configuration
to /etc/adjtime.)

It is possible I'm missing something, for example that there's some bug
that makes this not work properly, but at the moment it sounds as though
you're misunderstanding what "timedatectl set-local-rtc 1" does.

--
Colin Watson                                       [[hidden email]]

--
ubuntu-users mailing list
[hidden email]
Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-users