A. How to update the NTP servers used in configuration on cluster
Note: This procedure can be performed online on all nodes (database and quorum)
- Remove immutable attribute for /etc/chrony.conf file
# chattr -i /etc/chrony.conf
- Edit /etc/chrony.conf file and change/add only in this section:
... server <IP_or_name_NTP1> prefer iburst server <IP_or_name_NTP2> prefer iburst ...
- Restart the chronyd service
# systemctl restart chronyd
- Check if chronyd service is running after restart:
# systemctl status chronyd
- Check if chrony is synchronized:
# chronyc tracking # chronyc sources
Example:
[root@rac1 ~]# chronyc tracking Reference ID : D8EF2300 (time1.google.com) Stratum : 2 Ref time (UTC) : Fri Dec 18 15:08:39 2020 System time : 0.000838298 seconds fast of NTP time Last offset : +0.000428240 seconds RMS offset : 0.001808627 seconds Frequency : 22.558 ppm slow Residual freq : -1.062 ppm Skew : 0.054 ppm Root delay : 0.023304883 seconds Root dispersion : 0.001135960 seconds Update interval : 64.1 seconds Leap status : Normal
Fields to check in the output for these commands:
Ref time
This is the time (UTC) at which the last measurement from the reference source was processed.
[root@rac1 ~]# chronyc sources 210 Number of sources = 6 MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== ^+ time1.google.com 1 6 377 17 -2609us[-2609us] +/- 12ms ^+ time2.google.com 1 6 377 16 -1102us[-1102us] +/- 15ms ^* time3.google.com 1 6 377 17 -2033us[-3001us] +/- 11ms ^+ time4.google.com 1 6 377 17 -243us[ -243us] +/- 8935us =- rac2-ext.example.com 2 6 7 71 +36us[ -905us] +/- 80ms =- racq-ext.example.com 2 6 17 72 +2273us[+1333us] +/- 81ms
M
This indicates the mode of the source: ^ means a server = means a peer # indicates a locally connected reference clock
S
(Note: chronyc sources -v command will provide explanatory details on all output fields).
- Add the immutable attribute for /etc/chrony.conf
# chattr +i /etc/chrony.conf
Additionally, for changing timezone on the cluster refer the following article :
How to change timezone on a cluster