Chrony Faster Time Sync Configuration

Proxmox VE uses the service Chrony for time synchronisation. This service can still be optimized with regard to the query intervals of time servers with a separate configuration.

Default configuration

the standard update interval of Chrony is 513.4 :

root@PMX8:~# chronyc sources
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^* chronos.intern.thomas-kr>     2   9   377    87    +13us[ +133us] +/-   50ms

root@PMX8:~# chronyc tracking
Reference ID    : C0A86E0A (chronos.intern.thomas-krenn.com)
Stratum         : 3
Ref time (UTC)  : Mon Jun 03 08:20:04 2024
System time     : 0.000005868 seconds fast of NTP time
Last offset     : +0.000119389 seconds
RMS offset      : 0.000055728 seconds
Frequency       : 18.095 ppm fast
Residual freq   : +0.033 ppm
Skew            : 0.176 ppm
Root delay      : 0.009353423 seconds
Root dispersion : 0.030532107 seconds
Update interval : 513.4 seconds
Leap status     : Normal

This value is close to 512 and is calculated by Stratum and Poll(2⁹).

Configuration of Faster Time Sync

The Polling interval can be changed so that the time is synchronized more often:

root@PMX8:~# nano /etc/chrony/chrony.conf
# change to: server ntp.local minpoll 4 maxpoll 8 polltarget 32 iburst

root@PMX8:~# service chrony restart

root@PMX8:~# chronyc sources
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^* chronos.intern.thomas-kr>     2   4    77    11    +22us[  +41us] +/-   27ms

root@PMX8:~# chronyc tracking
Reference ID    : C0A86E0A (chronos.intern.thomas-krenn.com)
Stratum         : 3
Ref time (UTC)  : Mon Jun 03 08:25:56 2024
System time     : 0.000002181 seconds fast of NTP time
Last offset     : +0.000011445 seconds
RMS offset      : 0.000020134 seconds
Frequency       : 18.108 ppm fast
Residual freq   : +0.027 ppm
Skew            : 0.935 ppm
Root delay      : 0.009556593 seconds
Root dispersion : 0.021930953 seconds
Update interval : 16.0 seconds
Leap status     : Normal

This setting reduces the update interval to 16 seconds.

Author: Jonas Sterr Jonas Sterr has been working for Thomas-Krenn for several years. Originally employed as a trainee in technical support and then in hosting (formerly Filoo), Mr. Sterr now mainly deals with the topics of storage (SDS / Huawei / Netapp), virtualization (VMware, Proxmox, HyperV) and network (switches, firewalls) in product management at Thomas-Krenn.AG in Freyung.