[arch-general] UTC

Tom Gundersen teg at jklm.no
Mon Feb 18 19:40:10 EST 2013

On Mon, Feb 18, 2013 at 5:50 PM, Ralf Mardorf
<ralf.mardorf at alice-dsl.net> wrote:
> after a reboot there always is an offset of -3600 sec, when running
> ntpdate.
> # timedatectl status | grep local
>    RTC in local TZ: yes
> Warning: The RTC is configured to maintain time in the local time zone.
> This
>            RTC in UTC, by calling 'timedatectl set-local-rtc 0'.
> # timedatectl set-local-rtc 1
> Failed to issue method call: Input/output error

That message is disconcerting (at least the error message should have
been clearer). Could you have a look in "journalctl" (as root) to see
if you can get more information about what went wrong?

> Sometimes I don't get an output when running "timedatectl set-local-rtc 1".

That means it succeeded.

> # cat /etc/adjtime
> # ls -l /etc/localtime
> lrwxrwxrwx 1 root root 33 Feb 17 22:35 /etc/localtime ->
> /usr/share/zoneinfo/Europe/Berlin
> For my old Arch Linux install there wasn't this issue. I suspect I make a
> mistake, I'm missing something now.
> I already asked at the German forums, but until now without success:
> https://bbs.archlinux.de/viewtopic.php?id=23477
> FWIW I don't have a Windows installed, this machine is a *NIX multi-boot
> only. I'm aware about the drawbacks and advantages of both, the usage of
> UTC and local time and in 10 years I never experienced a drawback using
> local time. At the moment it's simply more comfortable for me, if I've got
> local time available for the BIOS. The reason for this should be
> unimportant for this thread.

If I remember correctly, one of the side effects of having your RTC in
localtime is that nothing will write to the RTC automatically. If the
RTC is in UTC and an ntp client is running (and your RTC is not too
much off), the kernel will write the system time to RTC every 11
minutes. However, that is not the case when your RTC is in localtime.

I suggest writing the time manually using 'hwclock' once you know you
have the correct system time (due to ntp).


I know you don't want to hear about the problems with localtime, but
to anyone else stumbling upon this: not having your RTC in UTC is
broken and will cause problems.

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