system-timesync.adoc

   1 Time Synchronization
   2 --------------------
   3 include::attributes.txt[]
   4 ifdef::wiki[]
   5 :pve-toplevel:
   6 endif::wiki[]
   7
   8 The {pve} cluster stack itself relies heavily on the fact that all
   9 the nodes have precisely synchronized time. Some other components,
  10 like Ceph, also refuse to work properly if the local time on nodes is
  11 not in sync.
  12
  13 Time synchronization between nodes can be achieved with the ``Network
  14 Time Protocol'' (`NTP`). {pve} uses `systemd-timesyncd` as NTP client
  15 by default, preconfigured to use a set of public servers. This setup
  16 works out of the box in most cases.
  17
  18
  19 Using Custom NTP Servers
  20 ~~~~~~~~~~~~~~~~~~~~~~~~
  21
  22 In some cases, it might be desired to not use the default NTP
  23 servers. For example, if your {pve} nodes do not have access to the
  24 public internet (e.g., because of restrictive firewall rules), you
  25 need to setup local NTP servers and tell `systemd-timesyncd` to use
  26 them:
  27
  28 .File `/etc/systemd/timesyncd.conf`
  29 ----
  30 [Time]
  31 Servers=ntp1.example.com ntp2.example.com ntp3.example.com ntp4.example.com
  32 ----
  33
  34 After restarting the synchronization service (`systemctl restart
  35 systemd-timesyncd`) you should verify that your newly configured NTP
  36 servers are used by checking the journal (`journalctl --since -1h -u
  37 systemd-timesyncd`):
  38
  39 ----
  40 ...
  41 Oct 07 14:58:36 node1 systemd[1]: Stopping Network Time Synchronization...
  42 Oct 07 14:58:36 node1 systemd[1]: Starting Network Time Synchronization...
  43 Oct 07 14:58:36 node1 systemd[1]: Started Network Time Synchronization.
  44 Oct 07 14:58:36 node1 systemd-timesyncd[13514]: Using NTP server 10.0.0.1:123 (ntp1.example.com).
  45 Oct 07 14:58:36 nora systemd-timesyncd[13514]: interval/delta/delay/jitter/drift 64s/-0.002s/0.020s/0.000s/-31ppm
  46 ...
  47 ----