This article applies to Domain Time II.

Published: 18 Apr 2007
Updated: 09 May 2007 (corrected typos)
Updated: 06 Nov 2007 (added note)

Question

How do I configure Domain Time II on a VMware system?

Answer

Because operating systems running as guests on VMware share the host's physical resources (such as CPU time and interrupt handling), their ability to keep their own accurate time is diminished.

You can install Domain Time II normally on guest OS virtual machines just as if those machines were running on actual stand-alone physical machines. However, due to the additional inaccuracies of the guest clocks in a virtual environment, you may find that Domain Time is having to spend most of its time correcting the clocks, to the point where you may not be able to acheive your desired clock accuracy.

For this reason, it is usually better practice to configure the guest operating systems to synchronize their clocks to the VMware host's clock using the VMware Tools "Time synchronization between the virtual machine and the host operating system" System Console function. Domain Time II Server or Client can still be installed on the guest to provide auditing and/or time server functionality, but the actual synchronization of the internal clock will be done using VMware Tools.

Important: If you are using the VMware Tools sync to host function, the time-setting function of any other time-synchronization software (such as Windows Time and Domain Time II) MUST be disabled to prevent contention over the system clock.

Note: We neither support nor warrant using Domain Time Server inside a guest OS. The virtual machine environment is not stable enough for time-serving purposes.

 

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Recommended configuration if you have the VMware Tools 'sync to host' function enabled:
• Install and use Domain Time II to synchronize the ESX host machine to your desired external time source. This will provide the greatest possible accuracy to the host system (and all its guests).

• If you are installing a Domain Time II Client on the guest OS:
  1. Use the VMware Tools System Console to enable the "Time synchronization between the virtual machine and the host operating system" function for the guest OS.

  2. Install Domain Time II Full Client. (Domain Time II Thin or Ultra-Thin Clients should not be installed in this mode, since their time-setting functions cannot be disabled.)

  3. On the Advanced tab of the Domain Time II Full Client control panel applet:
     • Be sure the Enable Test Mode checkbox is checked. This will allow the Client to run and respond to variance reports and Domain Time II Audit requests, but it will not try to set the system clock.

     • Use the Windows Time Startup: drop-down list to select Disabled (unless the guest OS is a Domain Controller or running the Windows Cluster Service, in which case this setting should be NoSync).

References
VMware Time Sync and Windows Time Service
Timekeeping in VMware Virtual Machines