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Guest time status reports VMIC Stratum 1 when host at Stratum 8 RRS feed

  • Question

  • I have a VMM/Hyper-V cluster where, for historical reasons, we run Meinberg NTP on all the Hyper-V hosts, syncing to an external NTP time service.

    Currently the external NTP time service is not working, so all the Hyper-V hosts are using their local onboard clock at Stratum 8 (which is NOT a GPS clock):

    Checking current status of NTP service with ntpq -p
         remote           refid      st t when poll reach   delay   offset  jitter
    ==============================================================================
    *LOCAL(0)        .LOCL.           8 l   22   64  377    0.000    0.000   0.000
     HOSTNAME        .XFAC.          16 u    -  128    0    0.000    0.000   0.000

    The VM guests running on these hypervisors show that they're syncing time with the VMIC Provider at Stratum 1:

    PS C:\windows\system32> w32tm /query /source
    VM IC Time Synchronization Provider
    PS C:\windows\system32> w32tm /query /status
    Leap Indicator: 0(no warning)
    Stratum: 1 (primary reference - syncd by radio clock)
    Precision: -6 (15.625ms per tick)
    Root Delay: 0.0000695s
    Root Dispersion: 0.0100002s
    ReferenceId: 0x564D5450 (source name:  "VMTP")
    Last Successful Sync Time: 20/06/2019 1:06:00 AM
    Source: VM IC Time Synchronization Provider
    Poll Interval: 6 (64s)
    

    I would have expected the VMIC provider to report Stratum 8. Does anyone know why the WMIC is reporting itself as Stratum 1? How can I change this behaviour?


    Monday, June 24, 2019 5:26 AM

All replies

  • Hi ,

    As far as I know ,when the Time Synchronization service is enabled for a VM, the VM's clock will match that of its host server.

    Please check if the following article is helpful:

    Time Synchronization in Hyper-V

    Best Regards,

    Candy


    Please remember to mark the replies as an answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com   

    Tuesday, June 25, 2019 3:18 AM
  • I have a VMM/Hyper-V cluster where, for historical reasons, we run Meinberg NTP on all the Hyper-V hosts, syncing to an external NTP time service.

    Currently the external NTP time service is not working, so all the Hyper-V hosts are using their local onboard clock at Stratum 8 (which is NOT a GPS clock):

    Checking current status of NTP service with ntpq -p
         remote           refid      st t when poll reach   delay   offset  jitter
    ==============================================================================
    *LOCAL(0)        .LOCL.           8 l   22   64  377    0.000    0.000   0.000
     HOSTNAME        .XFAC.          16 u    -  128    0    0.000    0.000   0.000

    The VM guests running on these hypervisors show that they're syncing time with the VMIC Provider at Stratum 1:

    PS C:\windows\system32> w32tm /query /source
    VM IC Time Synchronization Provider
    PS C:\windows\system32> w32tm /query /status
    Leap Indicator: 0(no warning)
    Stratum: 1 (primary reference - syncd by radio clock)
    Precision: -6 (15.625ms per tick)
    Root Delay: 0.0000695s
    Root Dispersion: 0.0100002s
    ReferenceId: 0x564D5450 (source name:  "VMTP")
    Last Successful Sync Time: 20/06/2019 1:06:00 AM
    Source: VM IC Time Synchronization Provider
    Poll Interval: 6 (64s)
    

    I would have expected the VMIC provider to report Stratum 8. Does anyone know why the WMIC is reporting itself as Stratum 1? How can I change this behaviour?


    I did some research on this, including reaching out to the Program Manager who is pretty much the authority on Windows Time. I did get quite a lot of good information, but I'm still not clear on any path where the VMIC could possibly report a stratum of 1. That seems to me like something is wrong. I do not have any way to replicate your environment, though. Have you tried the little things, like resetting the time service on a guest? What are your host and guest OS versions?

    He pointed me toward this article, not sure if there's any useful information in it for you: https://docs.microsoft.com/en-us/windows-server/networking/windows-time-service/accurate-time


    Eric Siron
    Altaro Hyper-V Blog
    I am an independent contributor, not an Altaro employee. I accept all responsibility for the content of my posts. You accept all responsibility for any actions that you take based on the content of my posts.

    Tuesday, June 25, 2019 1:32 PM
  • Hi ,

    Just want to confirm the current situations.

    Please feel free to let us know if you need further assistance.                   

    Best Regards,

    Candy


    Please remember to mark the replies as an answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com   

    Thursday, June 27, 2019 9:34 AM
  • Hi ,

    You could mark the useful reply as answer if you want to end this thread up.

    If there is anything else we can do for you, please feel free to post in the forum.

    Best Regards,

    Candy


    Please remember to mark the replies as an answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com   

    Monday, July 1, 2019 3:19 AM
  • Thanks for responding.

    Host and Guest OS version is Windows 2016 1607 - 10.0.14393

    Restarting the VM or win32tm service makes no change.

    Monday, July 22, 2019 6:22 AM
  • It does look like the Meinberg NTP server is what is causing the issue.

    When I look at another environment which does not use Meinberg, the Stratum is reported as +1 of the Hypervisor Stratum.

    Monday, July 22, 2019 6:44 AM