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
rhel time ntp oracle-linux ntpd
asked Jan 17 at 16:48
jonesy19jonesy19
326
add a comment |
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
rhel time ntp oracle-linux ntpd
asked Jan 17 at 16:48
jonesy19jonesy19
326
add a comment |
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
rhel time ntp oracle-linux ntpd
asked Jan 17 at 16:48
jonesy19jonesy19
326
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
rhel time ntp oracle-linux ntpd
rhel time ntp oracle-linux ntpd
asked Jan 17 at 16:48
jonesy19jonesy19
326
asked Jan 17 at 16:48
jonesy19jonesy19
326
asked Jan 17 at 16:48
jonesy19jonesy19
326
asked Jan 17 at 16:48
jonesy19jonesy19
326
asked Jan 17 at 16:48
jonesy19jonesy19
326
326
add a comment |
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
roaimaroaima
43.7k554117
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'NealDoug O'Neal
2,8521817
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 |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
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
roaimaroaima
43.7k554117
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.
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
roaimaroaima
43.7k554117
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.
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
roaimaroaima
43.7k554117
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
roaimaroaima
43.7k554117
answered Jan 17 at 19:17
roaimaroaima
43.7k554117
answered Jan 17 at 19:17
roaimaroaima
43.7k554117
answered Jan 17 at 19:17
roaimaroaima
43.7k554117
43.7k554117
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
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
@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, 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'NealDoug O'Neal
2,8521817
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'NealDoug O'Neal
2,8521817
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'NealDoug O'Neal
2,8521817
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'NealDoug O'Neal
2,8521817
answered Jan 17 at 19:01
Doug O'NealDoug O'Neal
2,8521817
answered Jan 17 at 19:01
Doug O'NealDoug O'Neal
2,8521817
answered Jan 17 at 19:01
Doug O'NealDoug O'Neal
2,8521817
2,8521817
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
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
@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
Thanks for the answer @Doug O'Neal
– jonesy19
Jan 17 at 19:59
add a comment |
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