[ntp:questions] NTP - best practice if there is a local stratum 2 server

Unruh unruh-spam at physics.ubc.ca
Wed Jul 1 07:45:00 UTC 2009

If you want accuracy, set up a gps clock. If not, pool is going to be good
enough. I was not impressed with bigben when I used it briefly but do not
remember the issues.

Dave <foo at coo.com> writes:

>I'm trying to set up the time on a couple of machines at the University 
>of Washington and have tried two ways:

>1) Sync both to the ntp pool - not very successful, as they kept 
>differing by enough to cause 'make' to say files were created in the 
>future by a few ms - no doubt due the NFS exported drives.

>2) Set one via ntpd (call is master) from the ntp pool, then the other 
>local machine (slave) read the time from the master. That appears to 
>work quite well. They at least agree on the time pretty closely now. The 
>absolute accuracy might not be as good as possible with a local time 
>server, but for practical purposes it works well.

>Searching around, I found that the university does in fact have their 
>own strtatum 2 time server - I assume in another department to where the 
>machines I'm using are located. The server is


>I assume, for absolute accuracy (which is not important here, but I'm 
>intersted), this is going to be better than any attempt to set the time 
>from the ntp pool. Is that correct?

>But setting the time from the local server is also going to be cause a 
>problem if that server fails for some reason.

>Is there any way to make use of a local server if it's working, and then 
>use the pool if its not?

>To be honest, this is all a bit academic, as there is no real practical 
>need to have an accuracy of better than a minute or two on these 
>machines. In fact, an hour wrong would not make much difference but it 
>might irritate a few people.

>But it is important the two machine agree with each other, as otherwise 
>files appear to be created in the future by a few ms, which screws up 
>the 'make' program some times.

>I respectfully request that this message is not archived by companies as
>unscrupulous as 'Experts Exchange' . In case you are unaware,
>'Experts Exchange'  take questions posted on the web and try to find
>idiots stupid enough to pay for the answers, which were posted freely
>by others. They are leeches.

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