[ntp:questions] Running NTP servers with different time offsets relative to some common "root" server?

Tobias Gierke tobias.gierke at voipfuture.com
Thu Jun 20 13:24:23 UTC 2019

Hi everyone,

I'm facing a NTP-relateded challenge at work and hope that somebody on 
this list has maybe solved a similar problem already:

- Our product is a system consisting of multiple components that may or 
may not run on the same host and all parts require time synchronization 
at all times because we're processing timestamped measurement data
- Our application does a lot of heavy computation triggered at the start 
of every minute (by crond)
- Since a lot of different application versions are deployed in the 
field and customers are slow to upgrade, we need to test many different 
versions of our application in our lab
- To ease hardware requirements for testing we run all those different 
versions of our application inside virtual machines, currently all 
synced to the same NTP server
- Since all those VMs are synchronized to the same server, all cron jobs 
on those VMs kick in at the same time, overloading the VM host periodically

I already looked into a simple solution (like being able to pass some 
magic "--offset XX seconds" option to ntpd) but it seems there is no 
such thing.

So my current idea is to

1.) have 4 different time servers that each are offset from all the 
others by 15 seconds (so server #1 would have offset 00 seconds, server 
#2 would have offset 15 seconds, etc.)
2.) configure those servers with ULC w/ PPS and hook-up the same PPS to 
all 4 servers OR have one PPS source for each server and have all of 
them sync to a common source (like a DCF77 time signal)

My problems are with the second step: I don't have a PPS source, I only 
have a Meinberg DCF600 USB 
but I couldn't find any documentation on how to use it as  a PPS source 
only (and ignore the actual "time" part of the synchronization). 
Furthermore I don't really want to buy 3 more of those clocks if I can 
help it (especially considering the fact that we might need even more 
different "time domains" as the number of VMs increases).

Any ideas?

Thanks in advance,

More information about the questions mailing list