Freebsd as a virtualbox HOST

R. Scott Evans freebsd-questions at
Fri Apr 4 14:32:01 UTC 2014

On 04/04/14 09:10, Maurizio Vairani wrote:
> On 04/04/2014 14:42, R. Scott Evans wrote:
>> On 04/03/14 04:58, Maurizio Vairani wrote:
>>> I am running FreeBSD 9.2-STABLE as a VirtualBox host with three Windows
>>> 7 VM from February 2013.
>>> The FreeBSD server has an Intel i7 with 64 GB RAM. The server and the
>>> VMs are very, very stable.
>>> I am writing this mail in a Windows 7 VM via Mac OS X Remote Desktop and
>>> seems to work on real PC.
>>> The only real, unique issue is  the VM clock drift: it is slow, very
>>> slow and I need to synchronize it every 5 minutes.
>>> In the log I can read from +105ms to +50,43s as adjustment.
>>> Regards
>>> Maurizio
>> I had the exact same problem with clock drift pop up on one of my
>> previously non-problematic FreeBSD VM's running on a FreeBSD host
>> about a month or two ago when all the NTP attacks started.  I locked
>> down NTP at that time on the guest and host systems but also made a
>> bunch of other changes trying to fix it so I'm not sure which was the
>> final solution but if it wasn't the NTP issue my next guess was that
>> it might have been a case of me updating the VirtualBox port (and
>> others) on the host and then not reloading the virtualbox kernel
>> module or rebooting the host after the port update.  Regardless, it's
>> not an issue for me any longer (ie, any drift I am seeing is minimal
>> and ntpd is able to keep up on it's own).
>> -scott
> Hi Scot,
> thank you for sharing your experience. I update the server nearly every
> day and when I update VirtualBox I shut down the VMs and reboot the server.
> But what version of FreeBSD and VirtualBox are you running ?
> Are you using Windows VMs ?
> Thanks
> Maurizio

I do have Windows VM's on it but they are bridged facing only my private 
LAN.  More importantly, they only get turned on when needed so any clock 
drift on them could easily have gone unnoticed.  The FreeBSD VM in 
question however is always on and bridged WAN facing.

If memory serves me, I think there have been 2 updates (maybe 3) to 
virtualbox since I had this problem and sadly I don't know what version 
it was at that time but currently its running the following:

FreeBSD 9.2-RELEASE-p3

Guest: FreeBSD 9.2-RELEASE-p3


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