Oracle 11gR2 RAC Cluster Verify Errors – NTP

During an installation of Oracle 11gR2 Real Application Clusters we encountered the following warning when running the cluster verification utility:

./bin/cluvfy stage -pre crsinst -n doclorau005,doclorau006 -verbose

Checking NTP daemon command line for slewing option "-x"
Check: NTP daemon command line
  Node Name                             Slewing Option Set?
  ------------------------------------  ------------------------
  doclorau006                           no
  doclorau005                           no
Result:
NTP daemon slewing option check failed on some nodes
PRVF-5436 : The NTP daemon running on one or more nodes lacks the slewing option "-x"
Result: Clock synchronization check using Network Time Protocol(NTP) failed

The solution was to re-configure the NTP server as follows:

Edit the /etc/sysconfig/ntpd configuration file and include the -x flag. For example, in our case we changed:

OPTIONS="-u ntp:ntp -p /var/run/ntpd.pid"

to

OPTIONS="-x -u ntp:ntp -p /var/run/ntpd.pid"

The NTP server was then restarted as follows:

service ntpd restart