Difference between revisions of "Time Synchronization"

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The Proxmox VE cluster stack itself relies heavily on the fact that all
 
The Proxmox VE cluster stack itself relies heavily on the fact that all
 
the nodes have precisely synchronized time. Some other components,
 
the nodes have precisely synchronized time. Some other components,
like Ceph, also refuse to work properly if the local time on nodes is
+
like Ceph, also won’t work properly if the local time on all nodes is
 
not in sync.
 
not in sync.
Time synchronization between nodes can be achieved with the “Network
+
Time synchronization between nodes can be achieved using the “Network
Time Protocol” (NTP). Proxmox VE uses systemd-timesyncd as NTP client
+
Time Protocol” (NTP). As of Proxmox VE 7, chrony is used as the default
by default, preconfigured to use a set of public servers. This setup
+
NTP daemon, while Proxmox VE 6 uses systemd-timesyncd. Both come preconfigured to
works out of the box in most cases.
+
use a set of public servers.
 +
If you upgrade your system to Proxmox VE 7, it is recommended that you
 +
manually install either chrony, ntp or openntpd.
 
Using Custom NTP Servers
 
Using Custom NTP Servers
In some cases, it might be desired to not use the default NTP
+
In some cases, it might be desired to use non-default NTP
 
servers. For example, if your Proxmox VE nodes do not have access to the
 
servers. For example, if your Proxmox VE nodes do not have access to the
public internet (e.g., because of restrictive firewall rules), you
+
public internet due to restrictive firewall rules, you
need to setup local NTP servers and tell systemd-timesyncd to use
+
need to set up local NTP servers and tell the NTP daemon to use
them:
+
them.
File /etc/systemd/timesyncd.conf
+
For systems using chrony:
 +
Specify which servers chrony should use in /etc/chrony/chrony.conf:
 +
server ntp1.example.com iburst
 +
server ntp2.example.com iburst
 +
server ntp3.example.com iburst
 +
Restart chrony:
 +
# systemctl restart chronyd
 +
Check the journal to confirm that the newly configured NTP servers are being
 +
used:
 +
# journalctl --since -1h -u chrony
 +
...
 +
Aug 26 13:00:09 node1 systemd[1]: Started chrony, an NTP client/server.
 +
Aug 26 13:00:15 node1 chronyd[4873]: Selected source 10.0.0.1 (ntp1.example.com)
 +
Aug 26 13:00:15 node1 chronyd[4873]: System clock TAI offset set to 37 seconds
 +
...
 +
For systems using systemd-timesyncd:
 +
Specify which servers systemd-timesyncd should use in
 +
/etc/systemd/timesyncd.conf:
 
[Time]
 
[Time]
Servers=ntp1.example.com ntp2.example.com ntp3.example.com ntp4.example.com
+
NTP=ntp1.example.com ntp2.example.com ntp3.example.com ntp4.example.com
After restarting the synchronization service (systemctl restart
+
Then, restart the synchronization service (systemctl restart
systemd-timesyncd) you should verify that your newly configured NTP
+
systemd-timesyncd), and verify that your newly configured NTP servers are in
servers are used by checking the journal (journalctl --since -1h -u
+
use by checking the journal (journalctl --since -1h -u systemd-timesyncd):
systemd-timesyncd):
 
 
...
 
...
 
Oct 07 14:58:36 node1 systemd[1]: Stopping Network Time Synchronization...
 
Oct 07 14:58:36 node1 systemd[1]: Stopping Network Time Synchronization...
Line 30: Line 48:
 
Oct 07 14:58:36 node1 systemd[1]: Started Network Time Synchronization.
 
Oct 07 14:58:36 node1 systemd[1]: Started Network Time Synchronization.
 
Oct 07 14:58:36 node1 systemd-timesyncd[13514]: Using NTP server 10.0.0.1:123 (ntp1.example.com).
 
Oct 07 14:58:36 node1 systemd-timesyncd[13514]: Using NTP server 10.0.0.1:123 (ntp1.example.com).
Oct 07 14:58:36 nora systemd-timesyncd[13514]: interval/delta/delay/jitter/drift 64s/-0.002s/0.020s/0.000s/-31ppm
+
Oct 07 14:58:36 node1 systemd-timesyncd[13514]: interval/delta/delay/jitter/drift 64s/-0.002s/0.020s/0.000s/-31ppm
 
...
 
...
 
</pvehide>
 
</pvehide>
 
<!--PVE_IMPORT_END_MARKER-->
 
<!--PVE_IMPORT_END_MARKER-->

Latest revision as of 10:27, 17 November 2021

The Proxmox VE cluster stack itself relies heavily on the fact that all the nodes have precisely synchronized time. Some other components, like Ceph, also won’t work properly if the local time on all nodes is not in sync.

Time synchronization between nodes can be achieved using the “Network Time Protocol” (NTP). As of Proxmox VE 7, chrony is used as the default NTP daemon, while Proxmox VE 6 uses systemd-timesyncd. Both come preconfigured to use a set of public servers.

Important If you upgrade your system to Proxmox VE 7, it is recommended that you manually install either chrony, ntp or openntpd.

Using Custom NTP Servers

In some cases, it might be desired to use non-default NTP servers. For example, if your Proxmox VE nodes do not have access to the public internet due to restrictive firewall rules, you need to set up local NTP servers and tell the NTP daemon to use them.

For systems using chrony:

Specify which servers chrony should use in /etc/chrony/chrony.conf:

server ntp1.example.com iburst
server ntp2.example.com iburst
server ntp3.example.com iburst

Restart chrony:

# systemctl restart chronyd

Check the journal to confirm that the newly configured NTP servers are being used:

# journalctl --since -1h -u chrony
...
Aug 26 13:00:09 node1 systemd[1]: Started chrony, an NTP client/server.
Aug 26 13:00:15 node1 chronyd[4873]: Selected source 10.0.0.1 (ntp1.example.com)
Aug 26 13:00:15 node1 chronyd[4873]: System clock TAI offset set to 37 seconds
...

For systems using systemd-timesyncd:

Specify which servers systemd-timesyncd should use in /etc/systemd/timesyncd.conf:

[Time]
NTP=ntp1.example.com ntp2.example.com ntp3.example.com ntp4.example.com

Then, restart the synchronization service (systemctl restart systemd-timesyncd), and verify that your newly configured NTP servers are in use by checking the journal (journalctl --since -1h -u systemd-timesyncd):

...
Oct 07 14:58:36 node1 systemd[1]: Stopping Network Time Synchronization...
Oct 07 14:58:36 node1 systemd[1]: Starting Network Time Synchronization...
Oct 07 14:58:36 node1 systemd[1]: Started Network Time Synchronization.
Oct 07 14:58:36 node1 systemd-timesyncd[13514]: Using NTP server 10.0.0.1:123 (ntp1.example.com).
Oct 07 14:58:36 node1 systemd-timesyncd[13514]: interval/delta/delay/jitter/drift 64s/-0.002s/0.020s/0.000s/-31ppm
...