[CentOS] Why the command 'service ntpd stop' cause the time reversed?

Jonathan Billings billings at negate.org
Thu Feb 12 02:52:32 UTC 2015


> On Feb 11, 2015, at 8:53 PM, David chen <c77_cn at 163.com> wrote:
> 
> The script should be executed at 14:00, the first line of the fragment also should indicate that the command 'service ntpd stop' have executed successfully, but why the second line timestamp(13:59:59) is less than the first line's(14:00:01)?

Because at 14:00, ntpd was stopped, then ntpdate was run which caused the clock to jump back in time, and ntpd started, and logged that it starts with the new time.  Syslog doesn't know the clock has changed, it's just logging what it thinks the current time is.  This is why you use ntpd instead of ntpdate out of cron -- ntpd is *supposed* to gradually change the clock until the OS clock matches the upstream NTPd server times.

I think you might want to check your ntpd configuration, because clearly its not keeping your clock in time.  Either that, or it's set up to talk to different clocks than what you're telling ntpdate to use.

--
Jonathan Billings <billings at negate.org>





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