Disabling Time Synchronization under Virtual PC 2007

When you have Virtual Machine Additions installed on Virtual PC we will automatically synchronize the virtual machines time with that of the host operating system.  For most people this is a "good thing" - but if this is something you want to disable you need to:

1. Stop the virtual machine in question.

2. Locate the .VMC file for the virtual machine.

3. Open the .VMC file in notepad.

   You can use a different editor - but notepad is the safest as it is guaranteed to not change our file format to something that is incompatible with Virtual PC (which other editors have been known to do).

4. Find the section of the .VMC file that looks like this:

   <integration>
   <microsoft>
   <mouse>
   <allow type="boolean">true</allow>
   </mouse>

   Bunch of other stuff that I am skipping over to save space...

   </microsoft>
   </integration>

5. Change it to look like this:

   <integration>
   <microsoft>
   <mouse>
   <allow type="boolean">true</allow>
   </mouse>
   <components>
   <host_time_sync>
   <enabled type="boolean">false</enabled>
   </host_time_sync>
   </components>

   Bunch of other stuff that I am skipping over to save space...

   </microsoft>
   </integration>

6. Close notepad and save the .VMC file.

7. Start the virtual machine under Virtual PC.

Note that this will not only disable the time synchronization that happens while the virtual machine is running - it will also disable the time synchronization that occurs when you start the virtual machine.  This means that unless you are using some other method for time synchronization (network server, etc...) time inside the guest operating system will become very incorrect very quickly.

Cheers,
Ben

Comments

• Anonymous
  November 28, 2007
  The comment has been removed

• Anonymous
  November 28, 2007
  The comment has been removed

• Anonymous
  November 29, 2007
  I think you could set up NTP with the physical host as NTP server and guests as NTP clients.  Then they'd handle the time zone difference.  Maybe that's exactly the reason for this blog posting.

• Anonymous
  December 06, 2007
  How can I enable time sync between a DOS6.22 VM and the host system?  As far as I can tell, the time displayed in a legacy, DOS-based comms program that runs on the DOS VM isn't sync'ed to the host's time, and it seems to progressively drift away from host time.  This means that the timestamps generated on events by the comms program are increasingly inaccurate.  Is there any way to get the DOS VM to time-sync to the host?

• Anonymous
  July 06, 2010
  I already could continue working with my virtual machine. Thanks in advace.

• Anonymous
  August 03, 2010
  I think you could set up NTP with the physical host as NTP server and guests as NTP clients.  Then they'd handle the time zone difference.  Maybe that's exactly the reason for this blog posting. www.stellentcomponents.in

• Anonymous
  October 23, 2010
  Does this also apply for Win7's Virtual PC? I have 2 vms running Windows Server 2008, disabled time sync as explained above. But when I change the time in my VM1 (a DC, with the time service disabled and stopped) it still changes back to my host time after a couple of seconds. The DC is NOT connected to the internet.

• Anonymous
  December 13, 2010
  Great to learn this tip. I have managed to setup my test environment for a cross year project following this instruction. Thanks.

• Anonymous
  June 25, 2012
  not working, it keeps syncronzing a few second after changing the datetime

• Anonymous
  February 04, 2014
  just can stop the time from sync-ing

• Anonymous
  June 19, 2014
  In win7 virtual pc time progressively drift away from host time by 15 sec per 1 minute

• Anonymous
  June 19, 2014
  Win7 virtual pc vmc file have in host_time_sync fields "frequency"(15) and "threshold"(10). It means then every 15 sec check if the difference more then 10 sec then sync time. As I said time drifts very quickly (15 sec per min, checked on pc and notebook). You will have the difference anyway up to 10 sec. I can set 1-1 for this fields. But I think it is not correct. How to make guest xp work the right time?

• Anonymous
  October 29, 2014
  Hi, i just need exactly opposite to this , my virtual machine clock is not in sync with local machine . on starting my virtual machine its showing exactly 1 hour delay to my local machine. example like if its 6:00pm in local machine its showing 5:00pm in my virtual machine (all my jobs i am scheduling from my virtual machine are kicking off 1 hour delay due to this ) Any suggestions please .