Arch Linux

solstice

Member

Registered: 2006-10-27

Posts: 237

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)

brebs

Member

Registered: 2007-04-03

Posts: 3,742

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.

bernarcher

Forum Fellow

From: Germany

Registered: 2009-02-17

Posts: 2,281

Re: DST and time clock shift

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.

brebs

Member

Registered: 2007-04-03

Posts: 3,742

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)

solstice

Member

Registered: 2006-10-27

Posts: 237

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)

brebs

Member

Registered: 2007-04-03

Posts: 3,742

Re: DST and time clock shift

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*.