NTP not working properly in Cloud (NTP)

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Environment

SUSE Linux Enterprise Server 12

Situation

It appears that the wrong server time is causing applications to fail. For example SAP Applications.

The issue described is only seen in cloud enviroments.

Checking the system time with

ntpq -p

shows an offset that is higher than 1000.

Trying to set the time again with ntpdate or other tools is only of temporary use as the time drifts again and soon out of range.

Resolution

To solve this it is advised to use chrony instead of ntp

   zypper in chrony
   systemctl disable ntpd
   systemctl stop ntpd

edit the config file

/etc/chrony.conf

******* SNIP *******
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#! pool pool.ntp.org iburst
server <put_in_IP_of_1st_timeserver> iburst
server <put_in_IP_of_2nd_timeserver> iburst
server <put_in_IP_of_3rd_timeserver> iburst
maxdistance 16.0
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# In first three updates step the system clock instead of slew
# if the adjustment is larger than 1 second.
makestep 1.0 3

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Allow NTP client access from local network.
#allow 192.168/16

# Serve time even if not synchronized to any NTP server.
#local stratum 10

# Specify file containing keys for NTP authentication.
#keyfile /etc/chrony.keys

# Specify directory for log files.
logdir /var/log/chrony

# Select which information is logged.
#log measurements statistics tracking
******* SNAP *******

and start the service

systemctl enable chronyd
systemctl start chronyd

Cause

It is unclear at this moment, why the ntp cannot cope and the drift gets out of control.

Once it surpasses 1000 ntp cannot cope anymore.

It seems that chrony works better in the cloud enviroment.

Disclaimer

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