Time Synchronization Issues /w Server 2012 Guest



  • I have at least one Server 2012 guest that has recently developed time synchronization issues. Every 30 minutes I'll see an entry like the following in the System event log:

    15aecc62-9bed-4cb1-a9b1-881fa6da6dc9-image.png

    The time drift on the surface seems insignificant, but it is wreaking havoc on various processes set up on this host.

    I believe this is an issue with the XenServer guest agent syncing time with the host. All of my XCP-ng hosts sync with a central NTP server (pair of Server 2016 Domain Controllers) which in turn sync with Stratum 1 NTP servers hosted by Hurricane Electric (one in San Jose, California and the other in New York, New York). So the time on the XCP-ng hosts and on my DCs is correct.

    I'm not sure where this time discrepancy is coming from. At any rate, I attempted to disable the XenServer guest agent's time sync process by modifying the following registry entries:

    HKLM\Software\Citrix\XenTools\HostTime
    HKLM\Software\Wow6432Node\Citrix\XenTools\HostTime

    According to posts on Citrix Discussions, setting these to either blank or "Local" should stop the host-guest time sync. However, in my case, these entries were already blank. I went ahead and set them to "Local" and then restarted all Citrix and Xen named services (since I cannot reboot this guest without pre-planning). This did not seem to make a difference.

    This guest is running under an up-to-date (as of last week anyway) XCP-ng 7.6 among a 16 member pool. I've migrated the VM to other members of the pool and the behavior has not changed. Also, my two Server 2016 domain controllers do not seem to be affected by this.

    I do have plans to upgrade to XCP-ng 8.0 this weekend, so I'm not sure if the behavior will change then.

    Curious if anyone has any ideas?


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