Talk:Network Time Protocol daemon

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Revision as of 14:27, 18 December 2011 by Kynikos (Talk | contribs) (ntpd -qg: re)

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This article has been created after splitting "Network Time Protocol" into this and OpenNTPD as discussed here -- Kynikos 16:03, 11 February 2011 (EST)

Update i18n links

Note that the i18n links still point to "Network Time Protocol" instead of "Network Time Protocol daemon": this should be changed if also the other wikis split the original article like this. -- Kynikos 16:58, 11 February 2011 (EST)

Fixed, also for the other langauges. -- Kynikos 05:49, 3 September 2011 (EDT)

ntpd -qg

Why is -g required in ntpd -qg in Using without daemon? It allows to adjust time by more than 15 min without a warning, which seems like a very specialized need. If there isn't something I don't know, I'd like to remove -g from there. - Corvinus 10:28, 3 December 2011 (EST)

Sorry for the delay of this answer. From man ntpd: Normally, ntpd exits with a message to the system log if the offset exceeds the panic threshold, which is 1000 s by default. This option (-g) allows the time to be set to any value without restriction; however, this can happen only once. If the threshold is exceeded after that, ntpd will exit with a message to the system log.
Not only the -g option causes no harm, but since you're running ntpd only at boot time, you can't predict whether the clock is off by more than 15 minutes or not, and if it is, without the -g option it won't be adjusted.
Googling it just a bit gives you some references, e.g. [1].
I'm restoring the -g option, but please feel free to continue the discussion if you can find some counter-arguments :)
-- Kynikos 16:17, 15 December 2011 (EST)
I disagree, -g would cause harm, because if clock is off by more than 15 min it means one of the following:
  • you run ntpd too rarely (must be several years perhaps),
  • your clock chip is hosed (no need setting it up),
  • some timezone/etc settings are incorrect and ntpd tries to do the wrong thing.
In either case, it's better to leave the clock as is and alert user (that's why this panic threshold is present in first place).
-- Corvinus 11:02, 16 December 2011 (EST)
But Kynikos stated that it only does the adjustment once, which makes argument #2 mostly a non-issue (unless he meant once per boot...). And #1 should be mostly a non-issue, especially because the wiki highly discourages users from not running ntpd in daemon mode. -- Jstjohn 13:18, 16 December 2011 (EST)
If they're non-issues, you don't need -g. If they are issues, you don't need -g either, since in this rare case it's better to be notified instead. -- Corvinus 14:47, 16 December 2011 (EST)
For "*your clock chip is hosed (no need setting it up)", by "non-issue" I meant that having -g wouldn't really hurt anything because if the clock chip is bad (or the CMOS battery is dead), the problem should manifest itself on the next boot of the system (assuming Kynikos was correct).
And I said that #1 should be a non-issue because if someone is only running ntpd very sporadically (i.e. not in daemon mode), then the sys admin probably doesn't know what he's doing. :3 (and that the wiki already discourages doing it like this in the first place) -- Jstjohn 14:59, 16 December 2011 (EST)
Eheh I've just reported what the man page says, and "this can happen only once" is referred only to the -g option, which could also be used without -q, thus leaving the daemon running. Of course at the next boot the major adjustment may happen again, so Corvinus has some points indeed. However I think the -qg usage should be mentioned since it seems quite common, see for example [2]. Let's just follow the Arch way and give the readers the freedom of choice: the relevant parts of this discussion should be wikified and put in the Network_Time_Protocol_daemon#Using_without_daemon section. For now I've added an Accuracy template.
-- Kynikos 10:24, 17 December 2011 (EST)
Done so. Remove template if correct.
If only every section in this wiki was composed with this amount of thought... :]
-- Corvinus 15:43, 17 December 2011 (EST)
Good job, I've reorganized the section a bit further and removed the Accuracy template. -- Kynikos 09:27, 18 December 2011 (EST)