Univention Bugzilla – Bug 30854
LOCAL driver should only be used when no timeserver is configured
Last modified: 2020-07-04 08:45:59 CEST
There is a problem when using the LOCAL clock: ntpd repeatedly switches between the upstream timeserver and the local clock, thus keeping the stratum and sync state as if synced to the local clock instead of the NTP clock. That makes the peer unattractive for downstream clients, which in turn prefer their local clock because the other servers are high stratum/local-reference too. The orphan mode should be investigated to replace the LOCAL clock. In theory the LOCAL clock is only required on the DC master and only if no other timeserver{,2,3} is configured; The DC backup/slave automaticall use the DC master/backup and should switch to orphan mode if upstream servers are temporarily not available. How to reproduce the problem: Master: timeserver=mammut.knut.univention.de reset clock ~35days back restart ntpd Backup: timeserver=mammut.knut.univention.de reset clock ~35days back restart ntpd Slave: reset clock ~35days back restart ntpd wait see the master/backup correct their clock but never reaching "sync_ntp" or a low stratum. observe master/backup regularly switching between ntp server and LOCAL. see the slave never correcting. References: http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver1.html "This driver is intended for use in an isolated network where no external source of synchronization such as a radio clock or modem is available." http://www.eecis.udel.edu/~mills/ntp/html/refclock.html "If a server with this driver is connected directly or indirectly to the public Internet, there is some danger that it can destabilize other clients." http://newsgroups.derkeiler.com/Archive/Comp/comp.protocols.time.ntp/2011-11/msg00026.html "is prone to switch to the LOCAL driver more often than is helpful." "Once it is selected, it continues to appear to be a better source than the network source, even after many polls, thanks to the 0 delay and root dispersion of reference clocks. This behavior is why this list/newsgroup is full of advice to avoid using the LOCAL driver," http://serverfault.com/questions/472455/why-is-ntp-syncing-to-local-rather-than-remote-server
I would prefere if there will be a ucr variable to switch, if local timeserver will be included in ntp.conf or just the values of the ucr variables timeserver[2,3]
This issue has been filed against UCS 3. UCS 3 is out of the normal maintenance and many UCS components have vastly changed in UCS 4. If this issue is still valid, please change the version to a newer UCS version otherwise this issue will be automatically closed in the next weeks.
There is a Customer ID set so I set the flag "Enterprise Customer affected".
This issue has been filed against UCS 3.1. UCS 3.1 is out of maintenance and many UCS components have vastly changed in later releases. Thus, this issue is now being closed. If this issue still occurs in newer UCS versions, please use "Clone this bug" or reopen this issue. In this case please provide detailed information on how this issue is affecting you.
Still relevant: Correct time is important for S4 domains. Until Bug #27728 is fixed the master uses the LOCAL clock by default.
This issue has been filed against UCS 4.2. UCS 4.2 is out of maintenance and many UCS components have changed in later releases. Thus, this issue is now being closed. If this issue still occurs in newer UCS versions, please use "Clone this bug" or reopen it and update the UCS version. In this case please provide detailed information on how this issue is affecting you.
This still is an issue.