Terje Mathisen wrote: > Andy wrote: >> About 10 years ago we used to have 2 seperate GPS receivers feeding >> into two Sparc servers via their serial port. I can't remember the >> version of NTP we ran however these were our stratum one servers, One >> of the Sparcs developed a fault on it's serial interface which delayed >> the input meaning the two stratum one servers started showing >> different time so all the statum 2 servers stopped trusting both >> stratum 1 servers as they could not determine which server, if any, >> was telling the truth. Ever since then we have always used at least 3 >> stratum one servers with seperate stratum zero sources to form a >> quorum so that startum 2 can differentiate the good from the bad. I >> believe this is set down as best practise in the ntp.org FAQ - this is >> a practical example of why this is wise. > > The "best practice" is in fact to use at least _four_ sources, that way > you can lose one and still have a voting group. > > Terje >
The magic numbers are 4, 5 and 7 protecting from the failure of one, two, or three servers respectively. If you can't do it with seven servers you have more serious problems! _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
