How to disable VirtualBox time sync from within the guest at runtime

Question

I have a VirtualBox VM running Centos 6.5 with Guest Additions installed and I need to be able to disable and enable time sync from within the guest at will. By default, the guest syncs its time with the host every 10 seconds[1], this is functionality built into the Guest Additions.

There are ways to disable the time sync but they are inadequate for my needs:

1. Disable the time sync at VM startup:

   VBoxManage setextradata "VM name" "VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" 1

2. Disable the guest additions from within the VM at runtime:

   sudo service vboxadd-service stop

The reasons they don't work for me are:

1. The first option only works at startup - I need to be able to do this at runtime
2. The second option stops other functions that I need from the guest additions

When I run sudo VBoxControl guestproperty enumerate I don't see anything to do with time syncing.

So… a way to disable and enable time sync from within a VirtualBox VM without disabling the vboxadd-service service please :)

[1] https://www.virtualbox.org/manual/ch09.html#disabletimesync - Section 9.13.4

Answer 1

You should be able to edit the vboxadd-service script on the client and add the --disable-timesync option. Then sudo service vboxadd-service restart and time sync should be disabled.

See also https://www.winklerweb.net/index.php/blog/11-tools/25-disabling-time-synchronization-in-virtualbox-ubuntu-16-04