Hyper-V Time Synchronization Service for Win2003 DC virtual machine
- I have 3 Windows 2008 servers with Hyper-V installed to support a lab domain (windows 2003).
I have 1 physical DC server that supports all major roles of the domain and 2 virtual DC servers (win2003).
The physical server is the one that keeps time synchronization with a reliable source.
The other 2 dc refers to the physical.
Typically, it is recommended to un-select "Time Synchronization" in all virtual machines in a domain. The Windows machines will synchronize with a DC.
Furthermore, a DC must synchronize with the PDC role machine.
I did so for all machines in the domain.
However, I got problems with the 2 virtual DCs at each reboot.
The win32time would never start.
I had to unregister, register and start win32time to make it work properly.
I found nothing on the web to correct this problem until I saw that the Hyper-V Time Synchronization Service on the virtual machine was running even if I un-selected "Time Synchronization" in the VM settings.
After disabling this Hyper-V Time Synchronization Service in the virtual DCs, the problem was gone!
I even used a GPO to disable this service for all virtual machines running in the domain.
I think that Microsoft should be aware of this problem and make Hyper-V to disable the Time Synchronization Service when the feature is un-selected in the VMs settings.
Serge B., Quebec
(hopefully you have found this useful)
All Replies
Hi,
In most hypervisor environments(Hyper-V is a hypervisor based technology), a VM will attempt to sync with the Host time.
I perform the following tests on several VMs and get the same symptom, the time in VMs will always sync with the host machine.
1. Uncheck "Time Synchronization” in VM’s settings
2. Disable the “Hyper-V Time Synchronization Service” inside the VMs.
3. Restart the VMs.
We have several post discussed the similar issue with yours, you can refer to:
Running expiring demos in Hyper-V
How to change time with Hyper-v R2?
Vincent Hu
· Hi,
I want to see if the information provided was helpful. Your feedback is very useful for the further research. Please feel free to let me know if you have addition questions.
Best regards,
Vincent Hu
- Hi,
your information is interesting, but this is not the same problem.
When running Hyper-V Time Synchronization Service on a VM hosting a DC, the Win32time service will stop with a fatal error.
This is why I had to desactivate Hyper-V Time Synchronization Service.
Win32time must run on a DC !
Otherwise many replication errors will appear in Active Directory.
Regards Hi,
Yes, the root cause is synchronization failure between W32Time and Hyper-V Time Synchronization Services. Unfortunately, the Hyper-V Time Synchronization Services will not be disabled if you only uncheck the Time Synchronization in VM’s settings, you may have to disable Hyper-V Time Synchronization Services in a virtual DC. Thanks for your understanding.
Time service
For virtual machines that are configured as domain controllers, disable time synchronization with the host through Integration Services. Instead, accept the default Windows Time service (W32time) domain hierarchy time synchronization.
Host time synchronization makes it possible for guest operating systems to synchronize their system clocks with the system clock of the host operating system. Because domain controllers have their own time synchronization mechanism, host time synchronization must be disabled on virtual machines that are configured as domain controllers. If domain controllers synchronize time from their own source and also synchronize time from the host, the domain controller time can change frequently. Because many domain controller tasks are tied to the system time, a jump in the system time could cause lingering objects to be left in the directory and replication to be stopped.
You can disable host time synchronization in the virtual machine settings in the Integration Services section of the Hyper-V Manager by clearing the Time Synchronization check box.
For more information, you can refer to:
Deployment Considerations for Virtualized Domain Controllers
http://technet.microsoft.com/en-us/library/dd348449(WS.10).aspx
Vincent Hu
· Hi,
I want to see if the information provided was helpful. Your feedback is very useful for the further research. Please feel free to let me know if you have addition questions.
Best regards,
Vincent Hu
