VMware Cloud Community
Jensational
Contributor
Contributor
‎02-01-2022 01:41 AM

ntp issues with VMware ESXi 7.0.3c

Hello,

I have some ntp warnings in the event log after installing or upgrading to VMware ESXi 7.0.3c on all servers. I already tried to restart the NTP Daemon Service and also chaned the options without success.

[...]
02/01/2022, 12:06:52 AM system clock no longer synchronized to upstream time servers
02/01/2022, 3:06:04 AM system clock synchronized to upstream time servers
02/01/2022, 4:06:05 AM system clock no longer synchronized to upstream time servers
02/01/2022, 5:43:46 AM system clock synchronized to upstream time servers
02/01/2022, 6:43:48 AM system clock no longer synchronized to upstream time servers
02/01/2022, 9:14:53 AM system clock synchronized to upstream time servers

Also in vmkernel.log:

[root@pmi-esx01:~] cat /var/log/vmkernel.log | grep NTPClock
[...]
2022-01-31T23:06:47.006Z cpu0:2098007)WARNING: NTPClock: 680: system clock apparently no longer synchronized to upstream time servers
2022-02-01T02:05:56.989Z cpu24:2109371)WARNING: NTPClock: 1764: system clock synchronized to upstream time servers
2022-02-01T03:05:58.009Z cpu0:2104433)WARNING: NTPClock: 680: system clock apparently no longer synchronized to upstream time servers
2022-02-01T04:43:46.001Z cpu20:2109371)WARNING: NTPClock: 1764: system clock synchronized to upstream time servers
2022-02-01T05:43:47.006Z cpu0:2097319)WARNING: NTPClock: 680: system clock apparently no longer synchronized to upstream time servers
2022-02-01T08:14:52.999Z cpu20:2109371)WARNING: NTPClock: 1764: system clock synchronized to upstream time servers
2022-02-01T09:15:15.872Z cpu37:2126587)WARNING: NTPClock: 1457: system clock stepped to 1643706915.000534000, no longer synchronized to upstream time servers
2022-02-01T09:29:46.001Z cpu2:2126606)WARNING: NTPClock: 1764: system clock synchronized to upstream time servers

 

NTP generally seems to work:

[root@pmi-esx01:~] ntpq -pn

remote refid st t when poll reach delay offset jitter
==============================================================================
10.XXX.0.1  .LOCL. 1 u 43 64 77 0.873 -1003.6 447.190
10.XXX.0.11 .LOCL. 1 u 33 64 177 0.868 -3.763 913.121

 

Version is:

root@pmi-esx01:~] vmware -v
VMware ESXi 7.0.3 build-19193900

 

Is this still a known issue?

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1 Reply
jlanders
VMware Employee
VMware Employee
‎02-01-2022 10:34 AM

Sorry to hear you're having problems. Since this worked for you before the update, let's assume your NOT running the Active Directory service which will also try to synchronize the host's system clock with the AD server. If you ARE running AD,  please see KB  Article 1035833 and follow the steps for disabling AD time synchronization if you wish to run NTP as well as AD on your ESXi host at the same time.

This earlier community discussion has some good tips on debugging your NTP configuration: https://communities.vmware.com/t5/ESXi-Discussions/NTP-Why-will-my-host-NOT-sync-time-to-the-NTP-sou...

In particular, your NTP configuration shows large offsets and jitter. This causes NTP to reject the time supplied by your upstream time sources. You'll most likely want to add the line "tos maxdist 30" (without the quotes) as a separate line to your /etc/ntp.conf configuration. This will allow NTP more flexibility in accepting a wider range of packets from your upstream NTP time sources.

With ESXi 7.0.3c, the best way to make this change permanent is copying the exiting /etc/ntp.conf into /tmp at the ESXi command line:

cp /etc/ntp.conf /tmp

Then, either use a text editor to add that new configuration line to the file in /tmp/ntp.conf or you can simply type:

echo "tos maxdist 30" >> /tmp/ntp.conf

This will append the line to the copy of your NTP configuration file.

Finally, at the command line, use the CLI to save your NTP configuration changes and restart the NTP service:

esxcli system ntp set -f /tmp/ntp.conf -e true

 

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