How-to: Time Synchronisation for UCS in Virtual Environments

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How-to: Time Synchronisation for UCS in Virtual Environments

Step 1 (default)

Sync time to hypervisor at startup (enabled by default, see here)

Step 2 (default)

Enable Network Time Protocol Daemon (ntpd) on UCS (default).
The ucr variables timeserver, timeserver2, timeserver3 and timeserver4 are used as references.
Domain clients like Windows sync their time to the domain controllers (Win AD or UCS).

Step 3

Disable permanent time synchronization from the hypervisor (ESXi, …) if enabled. Using time sync at boot is fine and enabled by default.

Set timeserver variables in UCS to sync to an external ntp-server (local or internet, ideally use multiple ones).

ucr set timeserver=0.de.pool.ntp.org
ucr set timeserver2=1.de.pool.ntp.org
ucr set timeserver3=2.de.pool.ntp.org
ucr set timeserver4=3.de.pool.ntp.org
systemctl restart ntp

Note
UCS systems by default install ntpd and synchronize to the UCS master. The mentioned ucr variables define additional servers from where they will sync time. Do NOT use UCS hosts for these variables.

Step 4

Configure UCS (at least) backup servers accordingly

Step 5

Monitor time synchronization with the tool “ntpq”.

root@backup:~# ntpq
ntpq> pe
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 LOCAL(0)        .LOCL.           9 l   8h   64    0    0.000    0.000   0.000
*master.multi.uc LOCAL(0)         6 u  916 1024  377    0.250    0.013   0.032

The sings in the first column indicate the current state. In details the most common items there are:

  • *: currently preferred server with most accurate time
  • + second best servers.
  • # 3rd best
  • - 4th best
  • . 5th best
  • x Time seems to be faulty. No synchronization from this host will happen
  • Space sign indicates ntpd did not get an reply from this host or it depends on the localhost
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