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

Michael Laajanen michael_laajanen at yahoo.com
Sun Jun 28 19:09:00 UTC 2009


Hi,

Dave wrote:
> 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
> 
> bigben.cac.washington.edu
> 
> 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.
> 
> 
Init file is /etc/inet/ntp.conf

Make it easy, sync them all to a ntp server, internal or external should
not matter for the simple use you plan for(make)

You have time.apple.com for instance and tick tock
server tick.usnogps.navy.mil
server tock.usnogps.navy.mil and nasa
ntp.nasa.gov


and many more

/michael




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