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#1 2009-03-29 09:57:43

solstice
Member
Registered: 2006-10-27
Posts: 164
Website

DST and time clock shift

hi.
DST is used since today in Europe.
so the change of timezone happened automatically here on archlinux. i.e. i have CEST
but the clock is not changed. i had to change the clock by one hour. (in fact i did not, it was ntpdate that i have setup in a cron job)
so it does not bother me so much, but from a technical point of view, i really would like to know how to make it happen automatically.

because some people report that it work all automatically for them (Timezone change and clock change)
i use HARDWARE=localtime in rc.conf but i was said it "should" work either with localtime or with UTC.
but is it working ? may be it works only with UTC ?

anyone can clarify why it works for some and not for others ? (i am not alone here)

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#2 2009-03-29 10:16:44

brebs
Member
Registered: 2007-04-03
Posts: 3,427

Re: DST and time clock shift

/usr/bin/ntpd should be running continuously as a daemon, not by cron. Then the time change will be instant.

Oh, and make sure you're using ntp rather than the inferior "openntp", to handle e.g. clock drift.

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#3 2009-03-29 10:27:33

bernarcher
Forum Fellow
From: Germany
Registered: 2009-02-17
Posts: 2,271

Re: DST and time clock shift

brebs wrote:

Oh, and make sure you're using ntp rather than the inferior "openntp", to handle e.g. clock drift.

Really? What are the issues, then (no flaming, just asking for information)?
I installed openntp because of its easier configuration, and it appears to handle clock drift well (> 2 sec/day without it).


To know or not to know ...
... the questions remain forever.

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#4 2009-03-29 10:43:43

brebs
Member
Registered: 2007-04-03
Posts: 3,427

Re: DST and time clock shift

For info, see:

http://www.gentoo-wiki.info/HOWTO_NTP_Using_OpenNTPD
http://www.gentoo-wiki.info/NTP
http://packages.debian.org/unstable/net/openntpd
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=306106

Edit:  Also, Linux-related upstream is dead, so Fedora didn't bother with it.

ntp configuration is easy, e.g. in /etc/ntp.conf:

logfile /var/log/ntp.log
driftfile /var/state/ntp.drift

restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery

restrict 127.0.0.1
restrict -6 ::1

server ntp.demon.co.uk prefer
server ntp2b.mcc.ac.uk
server ntp2c.mcc.ac.uk

Last edited by brebs (2009-08-08 00:09:59)

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#5 2009-03-29 10:57:21

solstice
Member
Registered: 2006-10-27
Posts: 164
Website

Re: DST and time clock shift

yes i have been blamed many times for using ntpdate.
but i use it once, every time i boot, daily. and never at the same hour. so i see no problem.
i don't see the point to run ntp daemon whatever the daemon is ntpd or openntpd. i don't see the point either to run ntpdate as i get a 0.5 s correction each day.

back to the original question: how is it possible the clock is handled correctly when DST changes for some and not for others ?

Last edited by solstice (2009-03-29 10:58:01)

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#6 2009-03-29 12:36:52

brebs
Member
Registered: 2007-04-03
Posts: 3,427

Re: DST and time clock shift

solstice wrote:

i don't see the point to run ntp daemon

So go to the ntp homepage and read its docs. Then, use the program as it's designed - as a *daemon*.

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