Stop VM time sync.

[emy101]

I have a windows 7 ultimate VM guest on an Ubuntu 16.04 host. I have guest additions installed but wish to permanently slow down the guest time rate to 7% of the host and prevent the guest from syncing its time to the host OS after its installation; these I did with the following at command line:

>>>VBoxManage setextradata "guest VM" "VBoxInternal/TM/WarpDrivePercentage" 7

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

The result is as expected with one exception: when the guest is shut down and restarted, its time is synced with the host; any suggest on permanently shutting down guest os time sync function will be appreciated.

[socratis]

any suggest on permanently shutting down guest os time sync function will be appreciated.

You can't do it as far as I know. These settings that you modified are valid as long as the VM is up and running. You'll have to keep reverting the clock at each VM's boot.

Synchronization *is* disabled. What you're looking for is the "initial value", which doesn't exist.

[Martin]

I remembered seeing a similar thread with a workaround some years ago:
viewtopic.php?p=122063#p122063

[socratis]

You're absolutely correct Martin, I stand corrected, there *is* an "initial value" (or offset if you prefer). For reference, here's the complete command:

VBoxManage <uuid|vmname> modifyvm --biossystemtimeoffset <msec>

This specifies a fixed time offset (milliseconds) of the guest relative to the host time. If the offset is positive, the guest time runs ahead of the host time.