Sunday, November 19, 2017

CRS-4700: The Cluster Time Synchronization Service is in Observer mode

This is very important to keep the time of cluster nodes synchronized across the cluster. Time difference among nodes can cause issues, and sometime it can cause the node(s) restart.

There are 2 ways of keeping the time synchronized across the RAC nodes: using NTP at OS level, or using Cluster Time Synchronization Service that runs as a RAC resource.

If issuing "crsctl check ctss" returns CRS-4700 message, it means you are already using OS level network time protocol to keep time of all RAC nodes synchronized. If you plan to use ctss (Cluster Time Synchronized Service), you would need to disable OS level NTP on all RAC nodes and then restart all nodes, or alternatively restart cluster services to have ctss start working for RAC nodes time synchronization.
To stop using NTP at OS level and start using CTSS, do as follows on all nodes.
For Linux 6
[root@salman11 ~]# /sbin/service ntpd stop
[root@salman11 ~]# chkconfig ntpd off
[root@salman11 ~]# mv /etc/ntp.conf /etc/
[root@salman11 ~]# rm /var/run/

For Linux 7
[root@salman11 ~]# systemctl stop chronyd
[root@salman11 ~]# systemctl disable chronyd
rm '/etc/systemd/system/'

--Delete or rename /etc/chrony.conf file
[root@salman11 ~]# mv /etc/chrony.conf  /etc/chrony.conf_old

As root user restart the whole cluster
#$GI_HOME/bin/crsctl stop cluster –all
#$GI_HOME/bin/crsctl start cluster -all

ctss should be running in “Active” mode now. Check the status as GI software owner

[grid@salman11 ~]$ crsctl check ctss
CRS-4701: The Cluster Time Synchronization Service is in Active mode.
CRS-4702: Offset (in msec): 0

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