Time Synchronization for CentOS7

Time Synchronization for CentOS7

Steps to set a server's time source to the NTP server:

  1. Use and set the coordinated universal time, UTC.

    timedatectl set-timezone UTC
  2. In chronyd.conf, add or modify the following IP address setting.

    1. When using SCS, use the Swarm-internal IP address.
      server {SCS Swarm-internal IP address} iburst

    2. To use a different NTP server:
      server {NTP server IP} iburst

Important

This must not be a Windows Directory SNTP server.

  1. Restart chrony:

> systemctl enable chronyd > systemctl restart chronyd
  1. Verify the time sources are correct.

chronyc sources -v

Verify there is an asterisk (*) next to one of the lines, indicating the time has been synchronized.

Example:

210 Number of sources = 1 .-- Source mode '^' = server, '=' = peer, '#' = local clock. / .- Source state '*' = current synced, '+' = combined , '-' = not combined, | / '?' = unreachable, 'x' = time may be in error, '~' = time too variable. || .- xxxx [ yyyy ] +/- zzzz || Reachability register (octal) -. | xxxx = adjusted offset, || Log2(Polling interval) --. | | yyyy = measured offset, || \ | | zzzz = estimated error. || | | \ MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== ^* telamon.tx.caringo.com 3 8 377 152 +5225ns[+7036ns] +/- 98ms
  1. Display tracking stats for the chrony deamon.

chronyc tracking -v

The tracking command displays parameters about the system’s clock performance.

An example of the output shown below.

Reference ID : 2D7D0114 (telamon.tx.caringo.com) Stratum : 4 Ref time (UTC) : Tue Jul 26 03:49:40 2022 System time : 0.000021030 seconds slow of NTP time Last offset : -0.000020990 seconds RMS offset : 0.000054007 seconds Frequency : 13.100 ppm slow Residual freq : -0.002 ppm Skew : 0.030 ppm Root delay : 0.004795842 seconds Root dispersion : 0.002171046 seconds Update interval : 1029.6 seconds Leap status : Normal
  1. Once the time is synchronized, sync the BIOS clock.

hwclock --systohc

 

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