How often (and when) does NTPD update the time?

I have an Oracle Linux 6 box (RHEL) and I have set up ntpd. I have run service ntpd start and chkconfig on. Now, if my date is incorrect and I reboot the box, it sets the time and date properly. That said, if the box is running, and I change the date using date --set "SEP 01 2000 00:00:00", it doesn't seem to update the time unless i reboot the box, or run service ntpd restart.

Am I doing something wrong? Is it working properly? My belief of how it should work is that if I change the date on the box, it should change it back within a reasonable amount of time.

Thanks

asked Jan 17 at 16:48

jonesy19

326

add a comment |

Am I doing something wrong? Is it working properly? My belief of how it should work is that if I change the date on the box, it should change it back within a reasonable amount of time.

Thanks

asked Jan 17 at 16:48

jonesy19

326

add a comment |

Am I doing something wrong? Is it working properly? My belief of how it should work is that if I change the date on the box, it should change it back within a reasonable amount of time.

Thanks

asked Jan 17 at 16:48

jonesy19

326

Am I doing something wrong? Is it working properly? My belief of how it should work is that if I change the date on the box, it should change it back within a reasonable amount of time.

Thanks

rhel time ntp oracle-linux ntpd

asked Jan 17 at 16:48

jonesy19

326

asked Jan 17 at 16:48

jonesy19

326

asked Jan 17 at 16:48

jonesy19

326

asked Jan 17 at 16:48

jonesy19

326

asked Jan 17 at 16:48

jonesy19

326

add a comment |

2 Answers
2

active

oldest

votes

If you change the clock underneath NTP while it's running, it will either start to slew the clock back - if it's not too far out - or simply give up in disgust and exit.

If you do change the clock a little, so that NTP remains running, it will assume that the change is due to a faulty clock, and will start to apply the correction longer term too, in an attempt to maintain correct time even when the network is disconnected. In an extreme case you can get worse clock drift over a longer period. At this point you need to remove the time adjustment files and reboot at least twice. (Not a happy situation.)

Bottom line: don't change the clock if you're using NTP.

answered Jan 17 at 19:17

roaima

44.3k555119

Thanks, this gives a nice detailed description to my issue. I was actually hoping that ntpd would solve all issues with time changes, but it doesn't. Either way, I tested it with an 8 minute difference and within 30 minutes it synced back to an accurate time. Thanks again

– jonesy19
Jan 17 at 19:58

@jonesy19 don't change the clock while NTP is running. Even for testing. Other than that, what other issues have you still got outstanding?

– roaima
Jan 17 at 20:28

Thanks, yeah I have realized it doesn't like the manual change. As for other issues, there are plenty, but none related to this. Thanks for the help. ;)

– jonesy19
Jan 18 at 21:21

add a comment |

Possible duplicate of this

ntpd will not try resetting the clock if it is too far out of sync.

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

If it's a duplicate, flag this question as such.

– Kusalananda
Jan 17 at 19:26

@Kusalananda can't flag cross-site answers

– roaima
Jan 17 at 19:41

Thanks for the answer @Doug O'Neal

– jonesy19
Jan 17 at 19:59

add a comment |

Your Answer

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "106"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);

);

draft saved

draft discarded

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f495116%2fhow-often-and-when-does-ntpd-update-the-time%23new-answer', 'question_page');

);

Post as a guest

Name

Required, but never shown

2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

If you change the clock underneath NTP while it's running, it will either start to slew the clock back - if it's not too far out - or simply give up in disgust and exit.

Bottom line: don't change the clock if you're using NTP.

answered Jan 17 at 19:17

roaima

44.3k555119

Thanks, this gives a nice detailed description to my issue. I was actually hoping that ntpd would solve all issues with time changes, but it doesn't. Either way, I tested it with an 8 minute difference and within 30 minutes it synced back to an accurate time. Thanks again

– jonesy19
Jan 17 at 19:58

@jonesy19 don't change the clock while NTP is running. Even for testing. Other than that, what other issues have you still got outstanding?

– roaima
Jan 17 at 20:28

Thanks, yeah I have realized it doesn't like the manual change. As for other issues, there are plenty, but none related to this. Thanks for the help. ;)

– jonesy19
Jan 18 at 21:21

add a comment |

If you change the clock underneath NTP while it's running, it will either start to slew the clock back - if it's not too far out - or simply give up in disgust and exit.

Bottom line: don't change the clock if you're using NTP.

answered Jan 17 at 19:17

roaima

44.3k555119

Thanks, this gives a nice detailed description to my issue. I was actually hoping that ntpd would solve all issues with time changes, but it doesn't. Either way, I tested it with an 8 minute difference and within 30 minutes it synced back to an accurate time. Thanks again

– jonesy19
Jan 17 at 19:58

@jonesy19 don't change the clock while NTP is running. Even for testing. Other than that, what other issues have you still got outstanding?

– roaima
Jan 17 at 20:28

Thanks, yeah I have realized it doesn't like the manual change. As for other issues, there are plenty, but none related to this. Thanks for the help. ;)

– jonesy19
Jan 18 at 21:21

add a comment |

If you change the clock underneath NTP while it's running, it will either start to slew the clock back - if it's not too far out - or simply give up in disgust and exit.

Bottom line: don't change the clock if you're using NTP.

answered Jan 17 at 19:17

roaima

44.3k555119

If you change the clock underneath NTP while it's running, it will either start to slew the clock back - if it's not too far out - or simply give up in disgust and exit.

Bottom line: don't change the clock if you're using NTP.

answered Jan 17 at 19:17

roaima

44.3k555119

answered Jan 17 at 19:17

roaima

44.3k555119

answered Jan 17 at 19:17

roaima

44.3k555119

answered Jan 17 at 19:17

roaima

44.3k555119

Thanks, this gives a nice detailed description to my issue. I was actually hoping that ntpd would solve all issues with time changes, but it doesn't. Either way, I tested it with an 8 minute difference and within 30 minutes it synced back to an accurate time. Thanks again

– jonesy19
Jan 17 at 19:58

@jonesy19 don't change the clock while NTP is running. Even for testing. Other than that, what other issues have you still got outstanding?

– roaima
Jan 17 at 20:28

Thanks, yeah I have realized it doesn't like the manual change. As for other issues, there are plenty, but none related to this. Thanks for the help. ;)

– jonesy19
Jan 18 at 21:21

add a comment |

Thanks, this gives a nice detailed description to my issue. I was actually hoping that ntpd would solve all issues with time changes, but it doesn't. Either way, I tested it with an 8 minute difference and within 30 minutes it synced back to an accurate time. Thanks again

– jonesy19
Jan 17 at 19:58

@jonesy19 don't change the clock while NTP is running. Even for testing. Other than that, what other issues have you still got outstanding?

– roaima
Jan 17 at 20:28

Thanks, yeah I have realized it doesn't like the manual change. As for other issues, there are plenty, but none related to this. Thanks for the help. ;)

– jonesy19
Jan 18 at 21:21

Thanks, this gives a nice detailed description to my issue. I was actually hoping that ntpd would solve all issues with time changes, but it doesn't. Either way, I tested it with an 8 minute difference and within 30 minutes it synced back to an accurate time. Thanks again

– jonesy19
Jan 17 at 19:58

@jonesy19 don't change the clock while NTP is running. Even for testing. Other than that, what other issues have you still got outstanding?

– roaima
Jan 17 at 20:28

Thanks, yeah I have realized it doesn't like the manual change. As for other issues, there are plenty, but none related to this. Thanks for the help. ;)

– jonesy19
Jan 18 at 21:21

add a comment |

Possible duplicate of this

ntpd will not try resetting the clock if it is too far out of sync.

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

If it's a duplicate, flag this question as such.

– Kusalananda
Jan 17 at 19:26

@Kusalananda can't flag cross-site answers

– roaima
Jan 17 at 19:41

Thanks for the answer @Doug O'Neal

– jonesy19
Jan 17 at 19:59

add a comment |

Possible duplicate of this

ntpd will not try resetting the clock if it is too far out of sync.

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

If it's a duplicate, flag this question as such.

– Kusalananda
Jan 17 at 19:26

@Kusalananda can't flag cross-site answers

– roaima
Jan 17 at 19:41

Thanks for the answer @Doug O'Neal

– jonesy19
Jan 17 at 19:59

add a comment |

Possible duplicate of this

ntpd will not try resetting the clock if it is too far out of sync.

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

Possible duplicate of this

ntpd will not try resetting the clock if it is too far out of sync.

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

answered Jan 17 at 19:01

Doug O'Neal

2,8801817

If it's a duplicate, flag this question as such.

– Kusalananda
Jan 17 at 19:26

@Kusalananda can't flag cross-site answers

– roaima
Jan 17 at 19:41

Thanks for the answer @Doug O'Neal

– jonesy19
Jan 17 at 19:59

add a comment |

If it's a duplicate, flag this question as such.

– Kusalananda
Jan 17 at 19:26

@Kusalananda can't flag cross-site answers

– roaima
Jan 17 at 19:41

Thanks for the answer @Doug O'Neal

– jonesy19
Jan 17 at 19:59

If it's a duplicate, flag this question as such.

– Kusalananda
Jan 17 at 19:26

@Kusalananda can't flag cross-site answers

– roaima
Jan 17 at 19:41

Thanks for the answer @Doug O'Neal

– jonesy19
Jan 17 at 19:59

add a comment |

draft saved

draft discarded

Thanks for contributing an answer to Unix & Linux Stack Exchange!

Please be sure to answer the question. Provide details and share your research!

But avoid …

Asking for help, clarification, or responding to other answers.

Making statements based on opinion; back them up with references or personal experience.

To learn more, see our tips on writing great answers.

draft saved

draft discarded

Post as a guest

Name

Required, but never shown

Name

Required, but never shown

Name

Required, but never shown

搜尋此網誌

mjhjmtu