Re: [chrony-users] Adding intentional offset with chronyd

[John Munoz <me@xxxxxxxxxxxxx>]

Thanks for the fast response Bill,

As far as why, Our broadcast delay is capable of taking the studio SMPTE timecode and offsetting it by the live delay time.  We are running a network show so we never have to ramp up or down, it’s always 40 seconds (unless a dump has occurred). All of the studio clocks pull their SMPTE from the output of the delay.  We are redesigning one of the studios and all the visual content is being displayed on a large amptec mutlivew output.  The amptec is only capable of using NTP, not SMPTE and since the time is just 40 seconds ahead of realtime most of the time, I was just wanting to create a npt server that could be used exclusively for the amptec of that studio.  

That you for the command to check the version, 

	[ec2-user@ip-10-31-0-80 ~]$ chronyc
	chrony version 3.5

The FAQ I read said that the offset began with 3.0 so I’m assuming I can do this with my version.

I’m pretty sure that the command I used in chrony.conf is where I messed up,

I just had added 

	Offset 4.0

...to the end of the cony.conf file and was getting the error I indicated previously.  This time I added the offset option to the end of the source server in the conf file,

	# Amazon Time Sync Service
	server 169.254.169.123 prefer iburst minpoll 4 maxpoll 4 offset 40

I also added it to the pool

	# Please consider joining the pool (http://www.pool.ntp.org/join.html).
	pool 2.rhel.pool.ntp.org iburst offset 40.0

Restarted the service.. but when I tested it didn’t appear to be reflecting the offset.

D:\Users\user>w32tm /stripchart /computer:10.10.11.10 (Real time server)
Tracking 10.10.11.10 [10.10.11.10:123].
The current time is 7/19/2020 10:16:40 PM.

D:\Users\user>w32tm /stripchart /computer:10.31.0.80 (Chrony offset server)
Tracking 10.31.0.80 [10.31.0.80:123].
The current time is 7/19/2020 10:16:44 PM.



Complete chrony.conf file

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
pool 2.rhel.pool.ntp.org iburst offset 40.0

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Enable hardware timestamping on all interfaces that support it.
#hwtimestamp *

# Increase the minimum number of selectable sources required to adjust
# the system clock.
#minsources 2

# Allow NTP client access from local network.
allow 10.0.0.0/8

# Serve time even if not synchronized to a time source.
#local stratum 10

# Specify file containing keys for NTP authentication.
keyfile /etc/chrony.keys

# Get TAI-UTC offset and leap seconds from the system tz database.
leapsectz right/UTC

# Specify directory for log files.
logdir /var/log/chrony

# Select which information is logged.
#log measurements statistics tracking

# Amazon Time Sync Service
server 169.254.169.123 prefer iburst minpoll 4 maxpoll 4 offset 40



> On Jul 19, 2020, at 10:02 PM, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:
> 
> Maybe if you tell us why you are trying to do that we could give you a better
> solution than what you are trying. (The offset command tells chrony to read
> the timestamps from the server as though they were out by 40 sec, not send
> those)
> 
> If you do chronyc
> it will tell you the version
> tunnel:0[unruh]>chronyc
> chrony version 3.4
> Copyright (C) 1997-2003, 2007, 2009-2018 Richard P. Curnow and others
> chrony comes with ABSOLUTELY NO WARRANTY.  This is free software, and
> you are welcome to redistribute it under certain conditions.  See the
> GNU General Public License version 2 for details.
> 
> Also why do you not show us exactly what the command is that you have in
> chrony.conf and also what the error message is.
> 
> 
> 
> William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
> Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
> UBC, Vancouver,BC _|_ Program in Cosmology |____ unruh@xxxxxxxxxxxxxx
> Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/
> 
> On Sun, 19 Jul 2020, John Munoz wrote:
> 
>> I’m trying to use chronyd in a broadcast environment and need to setup an NTP server that is 40 seconds ahead of realtime.
>> 
>> I tried editing /etc/chrony.conf and adding
>> 	offset 40.0
>> 
>> But when I went to relaunch I got an error on the line I added.
>> 
>> Jul 19 11:54:40  systemd[1]: Stopped NTP client/server.
>> Jul 19 11:54:40  systemd[1]: Starting NTP client/server...
>> Jul 19 11:54:40 chronyd[52990]: Invalid command at line 42 in file /etc/chrony.conf
>> Jul 19 11:54:40 systemd[1]: chronyd.service: Control process exited, code=exited status=1
>> Jul 19 11:54:40 systemd[1]: chronyd.service: Failed with result 'exit-code'.
>> Jul 19 11:54:40 systemd[1]: Failed to start NTP client/server.
>> 
>> I read somewhere that the offset command only works in new versions but I couldn’t find a command to tell me what version I’m running and yum update chrony returns “nothing to do”
>> 
>> 
>> Is what I’m trying to accomplish even possible?  I can’t figure out what I’m doing wrong.
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