Re: [ntp:questions] question regarding NTP configuration for clusters, and cluster time stability
Steve Kostecke schreef: What you really want is a decent quality PPS generator (e.g. Rubidium) which feeds an internal time server. Beware that ntp treats a PPS signal as a time source. A Rubidium oscillator is a frequency source, so it will slowly but inevitably run away, unless locked to a proper time source. Without such locking, the Rb should not be used as a PPS source (but could very well be a replacement for the clock's crystal). N ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
[ntp:questions] Large offset (200 seconds) during system boot
Hello, I encountered a somehow strange problem with ntpd after system boots. We powered down a whole HP-Enclosure with HP-Blades, all running ntp 4.2@1.1570 (packaged with RedHat Enterprise Linux Server 5.1 64 bit). All of these Blades use ntp.confs like the following : driftfile /var/lib/ntp/drift server blade0 iburst version 4 peer blade1 peer blade2 peer blade3 peer blade4 peer blade5 peer blade6 The blades were running fine before the shut down, with 6 ms offset as worst synchronization (measured against a Meinberg GPS 167 Radio Clock). After completely shutting down the enclosure and rebooting the blades showed an offset of 211000 ms (+- 1500 ms). ntpq -p showed that all sources had (more ore less) the same offset. After a restart of the ntp demon (via /etc/init.d/ntpd restart) - without changing anything in the config file - everything worked fine again... This also happens if I shut down only a single blade. 1) Has anybody else encountered this behaviour? 2) Has anybody found a workaround (especially with this version of ntp)? 3) Is there a known problem, if many ntpdemons (~16) start at approx. the same time? 4) Is there perhaps some well hidden synchronization mechanism by HP that sets the time in advance (in this case to a time 211 s off...) ? I might also wait for the release of ntp 4.2.6 if this would fix this behaviour, but my customer is quite sensitive about being an early adopter (regardless of how well tested the software is). My current workaround (if it can be called so) is restarting the ntpd after the system has finished booting. Best regards, Stefan Nottorf ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
[ntp:questions] Problem with system clock refresh
Good mornig. I have a trouble with NTP. I want a refresh my sistem clock (client) with a LAN Server each 5 minutes. I don’t know any parameter of NTP protocol for this configuration. It’s possible? The refresh it done usually, but takes a long time. I use Windows XP with meinberg software (client and server monitor). Thank you! PD: sorry for my poor english! :-) ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] question regarding NTP configuration for clusters, and cluster time stability
N writes: Beware that ntp treats a PPS signal as a time source. A Rubidium oscillator is a frequency source, so it will slowly but inevitably run away, unless locked to a proper time source. And after a century or so it may actually run away as far as several milliseconds. -- John Hasler jhas...@newsguy.com Dancing Horse Hill Elmwood, WI USA ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Problem with system clock refresh
JuanFran juanfranciscoj...@gmail.com wrote in message news:d693971e-be41-4a9b-9926-ed4a04f5b...@j9g2000vbp.googlegroups.com... Good mornig. I have a trouble with NTP. I want a refresh my sistem clock (client) with a LAN Server each 5 minutes. I dont know any parameter of NTP protocol for this configuration. Its possible? The refresh it done usually, but takes a long time. NTP does not work that way anyway, making it a meaningless way of measuring the closeness of two clocks. So, what is your real problem? Why do you want a five minute limit? Groetjes, Maarten Wiltink ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Problem with system clock refresh
JuanFran juanfranciscoj...@gmail.com wrote in message news:d693971e-be41-4a9b-9926-ed4a04f5b...@j9g2000vbp.googlegroups.com... Good mornig. I have a trouble with NTP. I want a refresh my sistem clock (client) with a LAN Server each 5 minutes. I don’t know any parameter of NTP protocol for this configuration. It’s possible? The refresh it done usually, but takes a long time. I use Windows XP with meinberg software (client and server monitor). Thank you! PD: sorry for my poor english! :-) Why do you want to do this, Juan? NTP will automatically adjust the interval between contacts to the server according to its own needs, and you don't normally need to set this. If you /really/ need to do this, you could edit the ntp.conf file with notepad to have entries similar to this: _ serverlan-addressmaxpoll 8iburst serverinternet-addressminpoll 10 serverinternet-addressminpoll 10 serverinternet-addressminpoll 10 serverinternet-addressminpoll 10 _ This sets the LAN-server to poll not less than once every 256 (2^^8) seconds, and have backup Internet servers which are polled at not less than 1024 (2^^10) second intervals. Cheers, David ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Problem with system clock refresh
On 23 nov, 15:02, David J Taylor david-tay...@blueyonder.not-this- bit.nor-this-part.co.uk.invalid wrote: JuanFran juanfranciscoj...@gmail.com wrote in message news:d693971e-be41-4a9b-9926-ed4a04f5b...@j9g2000vbp.googlegroups.com... Good mornig. I have a trouble with NTP. I want a refresh my sistem clock (client) with a LAN Server each 5 minutes. I don’t know any parameter of NTP protocol for this configuration. It’s possible? The refresh it done usually, but takes a long time. I use Windows XP with meinberg software (client and server monitor). Thank you! PD: sorry for my poor english! :-) Why do you want to do this, Juan? NTP will automatically adjust the interval between contacts to the server according to its own needs, and you don't normally need to set this. If you /really/ need to do this, you could edit the ntp.conf file with notepad to have entries similar to this: _ server lan-address maxpoll 8 iburst server internet-address minpoll 10 server internet-address minpoll 10 server internet-address minpoll 10 server internet-address minpoll 10 _ This sets the LAN-server to poll not less than once every 256 (2^^8) seconds, and have backup Internet servers which are polled at not less than 1024 (2^^10) second intervals. Cheers, David Hello! I work in a project that it need synchronize a LAN for collect data and images in real time. I need a lot of precision in the synchronization of all computers on my LAN. Thanks for your answer! I will try your solutions Regars! ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Problem with system clock refresh
JuanFran juanfranciscoj...@gmail.com wrote in message news:a26c31ce-d0bc-4fa2-a93b-d6c663a94...@j9g2000vbp.googlegroups.com... [] Hello! I work in a project that it need synchronize a LAN for collect data and images in real time. I need a lot of precision in the synchronization of all computers on my LAN. Thanks for your answer! I will try your solutions Regars! What precision do you want? I have some plots of what I see on my Windows systems here: http://www.satsignal.eu/mrtg/daily_ntp.html I have three stratum-1 servers based on Windows-2000 (Bacchus), Windows-XP (Feenix) and Windows-7 (Stamsund) all driven from Garmin GPS 18 LVC devices. If you needed a better stratum-1 server I would recommend a FreeBSD-based system. One Windows-XP system is synched to two of those stratum-1 servers, and that is the PC Narvik. You can see that it keeps within about 3ms of the correct time, and the offset has a strong periodic component because of the temperature variations in this domestic environment. If within 3ms isn't good enough, one approach might be to get a GPS 18LVC or other GPS receiver with a PPS (pulse per second) output, and building a box which would drive all the PCs you need with an RS232 signal derived from the PPS source. Cheers, David ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Problem with system clock refresh
JuanFran juanfranciscoj...@gmail.com writes: On 23 nov, 15:02, David J Taylor david-tay...@blueyonder.not-this- bit.nor-this-part.co.uk.invalid wrote: JuanFran juanfranciscoj...@gmail.com wrote in message news:d693971e-be41-4a9b-9926-ed4a04f5b...@j9g2000vbp.googlegroups.com... Good mornig. I have a trouble with NTP. I want a refresh my sistem clock (client) with a LAN Server each 5 minutes. I don=92t know any parameter of NTP protocol for this configuration. It=92s possible? The refresh it done usually, but takes a long time. I use Windows XP with meinberg software (client and server monitor). Thank you! PD: sorry for my poor english! :-) Why do you want to do this, Juan? =A0NTP will automatically adjust the interval between contacts to the server according to its own needs, and you don't normally need to set this. =A0If you /really/ need to do this, = you could edit the ntp.conf file with notepad to have entries similar to this= : _ server =A0 =A0lan-address =A0 =A0maxpoll 8 =A0 =A0iburst server =A0 =A0internet-address =A0 =A0minpoll 10 server =A0 =A0internet-address =A0 =A0minpoll 10 server =A0 =A0internet-address =A0 =A0minpoll 10 server =A0 =A0internet-address =A0 =A0minpoll 10 _ This sets the LAN-server to poll not less than once every 256 (2^^8) seconds, and have backup Internet servers which are polled at not less than 1024 (2^^10) second intervals. Cheers, David Hello! I work in a project that it need synchronize a LAN for collect data and images in real time. I need a lot of precision in the synchronization of all computers on my LAN. We have no idea what a lot of precision means. does it mean to the second? Or to the nanosecond? If you want better than milliseconds, a) do not use Windows, and b) get a GPS receiver with PPS for each of your computers. Thanks for your answer! I will try your solutions Regars! ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Problem with system clock refresh
JuanFran juanfranciscoj...@gmail.com writes: Good mornig. I have a trouble with NTP. I want a refresh my sistem clock (client) with a LAN Server each 5 minutes. I don=92t know any parameter of NTP protocol for this configuration. It=92s possible? The refresh it done usually, but takes a long time. I use Windows XP with meinberg software (client and server monitor). ntp takes a long time to settle down when first started. Thereafter it settles down to querying the remote clock about every 20 min or so ( which is enough to keep your system to an accuracy of bettern than milliseconds) PD: sorry for my poor english! :-) I am afraid I did not understand your last sentence in the first paragraph. ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
Re: [ntp:questions] Large offset (200 seconds) during system boot
Date: Mon, 23 Nov 2009 14:02:52 +0100 From: Nottorf, Stefan stefan.nott...@plath.de Sender: questions-bounces+oberman=es@lists.ntp.org Hello, I encountered a somehow strange problem with ntpd after system boots. We powered down a whole HP-Enclosure with HP-Blades, all running ntp 4.2@1.1570 (packaged with RedHat Enterprise Linux Server 5.1 64 bit). All of these Blades use ntp.confs like the following : driftfile /var/lib/ntp/drift server blade0 iburst version 4 peer blade1 peer blade2 peer blade3 peer blade4 peer blade5 peer blade6 The blades were running fine before the shut down, with 6 ms offset as worst synchronization (measured against a Meinberg GPS 167 Radio Clock). After completely shutting down the enclosure and rebooting the blades showed an offset of 211000 ms (+- 1500 ms). ntpq -p showed that all sources had (more ore less) the same offset. After a restart of the ntp demon (via /etc/init.d/ntpd restart) - without changing anything in the config file - everything worked fine again... This also happens if I shut down only a single blade. 1) Has anybody else encountered this behaviour? 2) Has anybody found a workaround (especially with this version of ntp)? 3) Is there a known problem, if many ntpdemons (~16) start at approx. the same time? 4) Is there perhaps some well hidden synchronization mechanism by HP that sets the time in advance (in this case to a time 211 s off...) ? I might also wait for the release of ntp 4.2.6 if this would fix this behaviour, but my customer is quite sensitive about being an early adopter (regardless of how well tested the software is). My current workaround (if it can be called so) is restarting the ntpd after the system has finished booting. Best regards, Stefan Nottorf I don't believe that this has anything to do with NTP, but is the hardware. I suspect that the HP bladeserver has a single hardware clock that is used to set the time for any blade at boot time. Unfortunately, this time is off by about 211 seconds and the system calls that would normally update the hardware clock are not doing so. This is not unreasonable when a single HW clock is used for multiple systems as one system could mess up the time for all of them if it mis-set the time. I am puzzled by one thing...where is the real time coming from? If all systems are off by 211 seconds, ntp is getting the correct time from somewhere, but I don't know where. If you have no external time source, I am confused. You mention a Meinberg, but I don't see any indication of how it fits in. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: ober...@es.net Phone: +1 510 486-8634 Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751 ___ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
