I have a setup of 8 VMWare VMs running across 4 EXSi hosts(IBM Blade Server). For some reasons I cannot connect these VMs or the EXSi hosts to the Internet or any other network. Now I want to synchronize the time on all these VMs. If I set the time on an EXSi host it affects only the VMs running on it. All these VMs(except the virtual center) are running on Ubuntu 12.10 64 bit. The virtual center is running on Suse Linux. Please let me know if you need any other information.

3 Answers 3


Set up an NTP server on your internal network and sync everything to it. If you don't care whether the time is actually accurate and just want to have everything synced to the same time then that will do it.

  • 1
    You could also run a GPS on the internal NTP server to get accurate time. May 30, 2013 at 6:13
  • @Reality Extractor, so in this case(one machine rule the time of all machines), when I want to change the time of the network, all I need to do is to change(e.g., using ntpdate) the time on the particular ruling machine, isn't it ?
    – John Wang
    Jul 11, 2014 at 9:09
  • Also, is it possible to setup a HA NTP service by multiple NTP server in the closed network, so one server can fail over to another ?
    – John Wang
    Jul 12, 2014 at 0:07

If you configure the VMware tools inside of each of the guest virtual machines, you have an option to synchronize time with the ESXi host. That is the way to accomplish this without using NTP.

  • But how do I synchronize VMs spread across multiple EXSi hosts?
    – user169253
    May 30, 2013 at 3:01
  • 1
    @Jay Have the ESXi hosts get their time from internal time source?
    – Vick Vega
    May 30, 2013 at 4:04

So given that:

  1. Your VMs cannot connect to any network
  2. Your VMs can be synchronized to EXSi host time
  3. Your EXSi hosts can connect to internet

You just should use ntp client on your EXSi hosts so that they are perfectly synced with each other.

  • And if you really cannot connect your EXSi hosts to any network, even with each other, what means do you have to exchange info between EXSi hosts? May 30, 2013 at 6:12
  • The EXSi hosts are connected to each other(172 series). The VMs are also connected to each other(192 series). But the EXSi and VMs cannot be connected to Internet.
    – user169253
    May 30, 2013 at 6:20
  • 1
    You can't install an NTP server on ESXi, it only runs the NTP client. May 30, 2013 at 8:10
  • So you should have means to connect your EXSi hosts to an NTP server. Either by setting up NTP server in 192 subnet or by connecting your subnet to internet. Jun 3, 2013 at 9:01

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