[ntp:questions] no drift-file on 2008 R2 vps and the time diff. is getting bigger and bigger?

Charles Elliott elliott.ch at comcast.net
Wed Sep 17 11:02:10 UTC 2014


>>>Really accurate time requires a physical machine
>>> and another operating system than Windows.

NUTS!  I regularly see sub-microsecond offsets; right now offset is 0.080
and jitter is 0.031.

I have 28.xx Mbps Internet service and use Gigabit Ethernet LAN.  I am also
using version 4.2.7p467 of NTPD and Windows 8.  I connect to a mixture of 9
stratum 1 and 2 external NTP servers that are physically close to me.  I
also use the HPET as the QPC via the following

run cmd as admin and paste "bcdedit /set {current} useplatformclock Yes".

Charles Elliott

> -----Original Message-----
> From: questions-bounces+elliott.ch=comcast.net at lists.ntp.org
> [mailto:questions-bounces+elliott.ch=comcast.net at lists.ntp.org] On
> Behalf Of Phil W Lee
> Sent: Tuesday, September 16, 2014 4:30 PM
> To: questions at lists.ntp.org
> Subject: Re: [ntp:questions] no drift-file on 2008 R2 vps and the time
> diff. is getting bigger and bigger?
> 
> Rob <nomail at example.com> considered 14 Sep 2014 11:35:54 GMT the
> perfect time to write:
> 
> >gooly <gooly at gmx.at> wrote:
> >>> When you want to sync it yourself, ntpd is not required at all,
> Windows
> >>> can do this itself.  Lookup the documentation for the windows time
> >>> service, you can configure it to use an external NTP server.
> >> I know! But w32tm is started to resync every x seconds. So it can
> happen
> >> that  w32tm changes the time while I am logging which will disable a
> >> later time-sort!
> >
> >In the later versions of Windows including 2008 R2 it is possible to
> >use a "real NTP" mode instead of the SNTP that was used before.
> >I think it should try to lock on the reference instead of jumping all
> >the time.  But it does a poorer job than ntpd.
> >However, when the clock in the system is so bad as you describe, both
> >of these programs will fail to lock it.
> >
> >>> It is not very accurate, but when you require really accurate time
> >>> a VPS is not for you.  Really accurate time requires a physical
> machine
> >>> and another operating system than Windows.
> >> But I can insist to require a clock with an offset less than 1
> second
> >> per hour or per 2 hours - no?
> >
> >Well, I see that Windows virtual machines in the hands of poor
> operators
> >have difficulty to be within 2 seconds all the time.  However, that is
> >two seconds overall, not per 2 hours.
> >Microsoft considers this "good enough" because they use time only for
> >kerberos, not for real timing work.
> >
> >Don't believe stories that it will never work on a VM.  I know I can
> >keep a Linux VM within 20ms all the time and within 2-5ms most of the
> >time.  However, Linux is not Windows and not all VMs are configured
> >reasonably.
> 
> It's certainly possible to run accurate tome on a VM, if the VM is
> running on a host which makes some reasonable attempt to keep good
> time in the first place.
> I run FreeBSD, Linux, and several versions of windows in this way -
> but I control the host they run on, and it keeps pretty good time.
> If the host machine is badly configured and outside the control of the
> VM operator, there is little that the operator of a VM running on it
> can do to resolve the situation.
> Except change providers.
> Of course, losing customers may just encourage the vendor to configure
> ntp properly on his host machines.
> 
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