[SOLVED]Automatic DST -- again

Leonid.I · 2009-11-01 17:31:59

Dear everyone,

It's Nov 1, which means that the issues about automatic daylight saving time adjustment are again relevant.

Actually, I have a quite general question: How exactly does the Linux kernel (in the Arch way, of course) handle the above-mentioned transition?

As far as I read on Novell's website (which is also mentioned in timezone archwiki), if HARDWARECLOCK is set to UTC, then the time adjustment will occur automatically, whether the system is running or not, when the DST began/ended. On the other hand, if HARDWARECLOCK=localtime, linux should not touch the time at all.

However, I have two Arch systems, out of which one (desktop) is up since September, and I turned on the other (laptop) in the morning of Nov 1. The desktop correctly subtracted one hour (without NTPD, because there were no logs about the time change ), while the laptop required openntpd to move the time back. Both systems are on localtime (it's a good question why, since there is no Windows ).

So, how should I understand this?

Thanks,
L.

Last edited by Leonid.I (2009-11-15 21:49:46)

fsckd · 2009-11-01 17:45:25

Hmm interesting, my desktop didn't update either. It too is localtime.

Of course, this means I'll have to reboot into Debian and let it's ntp stuff handle it. Unfortunately, I'll have to deal with that stupid file-system-was-last-mounted-in-the-future-please-fsck-manually error. How will Arch handle time traveling?

Leonid.I · 2009-11-01 18:12:46

fsckd wrote:

Hmm interesting, my desktop didn't update either. It too is localtime.
Of course, this means I'll have to reboot into Debian and let it's ntp stuff handle it. Unfortunately, I'll have to deal with that stupid file-system-was-last-mounted-in-the-future-please-fsck-manually error. How will Arch handle time traveling?

Was your desktop working, when the time change occured (around 2.00am)? My laptop was not, and I guess that is the problem, but I need someone to confirm this, because I am not a pro in this stuff.

Regarding your question, your system should be fine, after the clock has been changed. The only thing, PLEASE DO NOT REPEAT MY MISTAKE, AND KEEP YOUR SYSTEM RUNNING FOR AT LEAST AN HOUR, BEFORE REBOOTING. Otherwise, you'll have exactly the problem you mentioned. I had to use the Arch Live CD to get the laptop operational again...

Why can't you use openntpd from Arch?

Last edited by Leonid.I (2009-11-01 18:14:49)

fsckd · 2009-11-01 18:37:49

This was a test install and doesn't have everything I'd have in a normal install.

No, I did not have the system running at 2 a.m. My understanding is, with hardwareclock set to localtime and in absence of any ntp setup, the time should remain the same provided the machine was not running at the point of change. The reason is, Arch has no idea if another system has already updated the time.

Leonid.I · 2009-11-15 21:50:58

Yes, thanks, you reply made me do some research and now I understand the issue.

Arch Linux

#1 2009-11-01 17:31:59

[SOLVED]Automatic DST -- again

#2 2009-11-01 17:45:25

Re: [SOLVED]Automatic DST -- again

#3 2009-11-01 18:12:46

Re: [SOLVED]Automatic DST -- again

#4 2009-11-01 18:37:49

Re: [SOLVED]Automatic DST -- again

#5 2009-11-15 21:50:58

Re: [SOLVED]Automatic DST -- again

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