Re: [Dovecot] Time just moved backwards error even with ntpd
On some FreeBSD 6.2 systems I was solved this problem just by adding to crontab: @hourly/sbin/sysctl `/sbin/sysctl -e machdep.adjkerntz` >/dev/null 2>&1 For some explanation, see: http://lists.freebsd.org/pipermail/freebsd-hackers/2005-August/013383.html Quote follows: ... It seems that CMOS clock is updated using resettodr(9) function. There seem to be only a few occasions when this function is called: 1. clock_settime(ClOCK_REALTIME) // through kern_time.c:settime() 2. settimeofday() // through kern_time.c:settime() 3. machdep.adjkerntz sysctl is set I believe that ntpd calls *settime-family* functions *only* if time offset is *larger* than *128ms* (or maybe I am thinking about ntpdate), but normally it uses ntp_adjtime() to adjust time keeping. Obviosuly, a system running ntpd with good enough hardware clock and good enough connection to good enough ntp server(s) would use the latter method all of the time after some initial stabilization period. But it seems that time changes are *never propagated to CMOS* in this case, ... Alexander
Re: [Dovecot] Time just moved backwards error even with ntpd
On Sat, Jan 19, 2008 at 11:07:58AM -0500, Charles Marcus wrote: On 1/19/2008 Luigi Rosa wrote: >> On one hand we have Dovecot that kill itself until someone kicks it back >> on, on the other hand we have just some errors on the logfile. >> >> Well, IMHO at least there could be a configuration parameter that allows >> me to choose between a service that kills itself and some errors on a >> logfile and maybe a temporary service failure. >> >> Each SysAdmin could weight the consequences and choose the option he/she >> thinks is more appropriate to his/her server. Accurate time is CRITICAL for a mail server (and most any other server as well). I think the current behavior is reasonable. Fix the actual problem (server time being incorrect at boot time), and this is not an issue. Even without this problem, it may be wise to add a script to check often if dovecot is running, and start it if it is not. That way your downtime caused by this issue will be minimal. and/or add more servers so users won't notice any downtime except possibly being disconnected once.
Re: [Dovecot] Time just moved backwards error even with ntpd
On 1/19/2008 Luigi Rosa wrote: On one hand we have Dovecot that kill itself until someone kicks it back on, on the other hand we have just some errors on the logfile. Well, IMHO at least there could be a configuration parameter that allows me to choose between a service that kills itself and some errors on a logfile and maybe a temporary service failure. Each SysAdmin could weight the consequences and choose the option he/she thinks is more appropriate to his/her server. Accurate time is CRITICAL for a mail server (and most any other server as well). I think the current behavior is reasonable. Fix the actual problem (server time being incorrect at boot time), and this is not an issue.
Re: [Dovecot] Time just moved backwards error even with ntpd
Gunter Ohrner said the following on 19/01/08 16:51: That's why I suggested to use ntpdate to force the correct time to be set before ntpd even starts and the ntp init script returns. Admittedly, this won't work if you have no network connectivity during boot up, but if you have, this paticular problem is most likely solved. I don't remember if there already is an ntpdat on that particular machine, but many ntpd startup script have an ntpdate entry. I'll check. But I don't think that this is the point. According to Dovecot Wiki, "If all else fails, you can just go and remove the error checking code from src/lib/ioloop.c. It's unlikely that anything will break badly, but you might get some errors logged once in a while." On one hand we have Dovecot that kill itself until someone kicks it back on, on the other hand we have just some errors on the logfile. Well, IMHO at least there could be a configuration parameter that allows me to choose between a service that kills itself and some errors on a logfile and maybe a temporary service failure. Each SysAdmin could weight the consequences and choose the option he/she thinks is more appropriate to his/her server. Ciao, luigi -- / +--[Luigi Rosa]-- \ Success is 99% failure. --Soichiro Honda
Re: [Dovecot] Time just moved backwards error even with ntpd
Karsten Bräckelmann said the following on 19/01/2008 13.26: But the system clock was 45 minutes ahead, so: No. :) You'r right, my mistake. Exactly one hour. Doesn't strike me as a coincidence... Don't know. That machine had a very long uptime. The system is configured to have the hardware clock on GMT. Ciao, luigi Ciao, luigi -- / +--[Luigi Rosa]-- \ We must acknowledge once and for all that the purpose of diplomacy is to prolong a crisis. --Spock, "The Mark of Gideon"
Re: [Dovecot] Time just moved backwards error even with ntpd
Gunter Ohrner said the following on 19/01/08 16:47: Mh, sounds as if the system clock is set to "local time", including DST changes, and the system clock had not yet been adjusted... I know why I use UTC for the system clock on my machines... ;) Probably. As I said the server lost power without a clean shutdown and its uptime was very high. Ciao, luigi -- / +--[Luigi Rosa]-- \ If it's working, the diagnostics say it's fine. If it's not working, the diagnostics say it's fine.
Re: [Dovecot] Time just moved backwards error even with ntpd
Ralf Hildebrandt said the following on 19/01/2008 13.16: Solution: Start ntpdate/ntpd FIRST. It's what I did, but it could not solve this specific issue. Unfortunately, server and ADSL modem router went back online together and the ADSL router takes more time to go online than the server (blame it on Linux and fast processor :) I was able to replicate this scenario: the ADSL modem/router connects to Internet few second after I get the login on Linux, so even starting ntpd right after the network and dovecot as last service could not help. Ciao, luigi -- / +--[Luigi Rosa]-- \ Q: And this, I'm particularly proud of - behind the headlights, stinger missiles! James Bond: Excellent, just the thing for unwinding after a rough day at the office. Q: Need I remind you, 007, that you have a license to kill, not to break traffic laws. --007 Goldeneye
Re: [Dovecot] Time just moved backwards error even with ntpd
On Sat, 2008-01-19 at 12:46 +0100, Luigi Rosa wrote:
> Scenario: server PC abruptly switched off due to power cable problems
> (an UPS cannot solve this issue), so during shutdown Linux was not
This sounds like rather extreme, exceptional circumstances. And actually
an infrastructure problem, rather than software. ;)
> able to resinchronize the system clock. After a few hours the server
> come back on, Linux booted and the services (ntpd, dovecot and many
> others) started
>
> But the system clock was 45 minutes ahead, so:
No. :)
> Jan 19 11:13:39 gw ntpd[2112]: synchronized to LOCAL(0), stratum 10
> Jan 19 11:13:39 gw ntpd[2112]: kernel time sync disabled 0041
> Jan 19 11:14:43 gw ntpd[2112]: synchronized to 62.48.35.100, stratum 2
> Jan 19 10:31:55 gw ntpd[2112]: time reset -3600.221385 s
> Jan 19 10:31:55 gw ntpd[2112]: kernel time sync enabled 0001
> Jan 19 10:31:55 gw dovecot: Time just moved backwards by 3600 seconds.
> This might cause a lot of problems, so I'll just kill myself now.
> http://wiki.dovecot.org/TimeMovedBackwards
Exactly one hour. Doesn't strike me as a coincidence...
guenther
--
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Re: [Dovecot] Time just moved backwards error even with ntpd
* Luigi Rosa <[EMAIL PROTECTED]>: > Scenario: server PC abruptly switched off due to power cable problems (an > UPS cannot solve this issue), so during shutdown Linux was not able to > resinchronize the system clock. After a few hours the server come back on, > Linux booted and the services (ntpd, dovecot and many others) started > > But the system clock was 45 minutes ahead, so: > > Jan 19 11:13:39 gw ntpd[2112]: synchronized to LOCAL(0), stratum 10 > Jan 19 11:13:39 gw ntpd[2112]: kernel time sync disabled 0041 > Jan 19 11:14:43 gw ntpd[2112]: synchronized to 62.48.35.100, stratum 2 > Jan 19 10:31:55 gw ntpd[2112]: time reset -3600.221385 s > Jan 19 10:31:55 gw ntpd[2112]: kernel time sync enabled 0001 > Jan 19 10:31:55 gw dovecot: Time just moved backwards by 3600 seconds. This > might cause a lot of problems, so I'll just kill myself now. > http://wiki.dovecot.org/TimeMovedBackwards Solution: Start ntpdate/ntpd FIRST. -- Ralf Hildebrandt ([EMAIL PROTECTED]) [EMAIL PROTECTED] Postfix - Einrichtung, Betrieb und Wartung Tel. +49 (0)30-450 570-155 http://www.arschkrebs.de I realise computers suck. The only reason why they are a hobby of mine is because I enjoy pain!
[Dovecot] Time just moved backwards error even with ntpd
Scenario: server PC abruptly switched off due to power cable problems (an UPS cannot solve this issue), so during shutdown Linux was not able to resinchronize the system clock. After a few hours the server come back on, Linux booted and the services (ntpd, dovecot and many others) started But the system clock was 45 minutes ahead, so: Jan 19 11:13:39 gw ntpd[2112]: synchronized to LOCAL(0), stratum 10 Jan 19 11:13:39 gw ntpd[2112]: kernel time sync disabled 0041 Jan 19 11:14:43 gw ntpd[2112]: synchronized to 62.48.35.100, stratum 2 Jan 19 10:31:55 gw ntpd[2112]: time reset -3600.221385 s Jan 19 10:31:55 gw ntpd[2112]: kernel time sync enabled 0001 Jan 19 10:31:55 gw dovecot: Time just moved backwards by 3600 seconds. This might cause a lot of problems, so I'll just kill myself now. http://wiki.dovecot.org/TimeMovedBackwards Ciao, luigi -- / +--[Luigi Rosa]-- \ Spoon boy: Do not try and bend the spoon. That's impossible. Instead... only try to realize the truth. Neo: What truth? Spoon boy: There is no spoon. Neo: There is no spoon? Spoon boy: Then you'll see, that it is not the spoon that bends, it is only yourself. --The Matrix
