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Major clock drift on root as soon as a VM is started
Major clock drift on root as soon as a VM is started
- [Reported earlier this year by someone else with Server 2008, but that thread was incorrectly marked as "answered": the user just switched to VMware...]
I'm having this problem with Windows Server 2008 R2 (x64) on my home server (Intel Core 2 Duo system, Asus P5B-V board). The root OS clock slows down when a VM is started.
Using W32TM /stripchart to monitor the clock, it's clear that starting any VM will immediately cause the clock to slow down with about 10 msec per second. When the VM is stopped, the drift decreases to the original (acceptable) value.
While the VM is running, I noticed that a "Kernel-General" event message pops up in the root OS event log every two hours, saying that the clock was set to a new time. Time gap at that point is about 2 minutes.
I have no time critical applications, but still I like the clock to be within a few seconds...
Also tried Meinberg NTP, but with that much drift, NTP will not even recognize a valid time source.
Does anyone know a solution for this problem?
regards,
Peter
All Replies
- Yes, this clock drift issue keeps coming up and I know it is being discussed by the Hyper-V team.
The way that you report the problem is that the closk of hte Host is drifting. Is that correct?
I am curious: Does the drifting of the Host clock have any negative effect on your environment?
Or is it just an annoyance?
There are ways to prevent the VMs from time syncing with the host - As it is generally the drift being applied to the VMs that is the real bugger and causes all sorts of problems, even with systems that I would call 'medium' time sensitive.
Brian Ehlert (hopefully you have found this useful) - I'm speaking to the product team in person this morning about this issue.
- Hiya,
try to disable the time synchronization for your childs.
On host open Hyper-v Manager,
click settings for your VM,
Go down to Integration Services offered and untic time Synch.
That "solved" our time synch issues. - Hi Brian, thanks for your message. I'm happy that this issue is being discussed by the Hyper-V team.
It is indeed the host that has the clock drift. As I understand, with Hyper-V architecture, it is more accurate to call this the 'root'.
I know that there is a way to prevent the guest VMs from syncing with the host, but my focus is with the root cause of this problem.
I wasn't aware of the problem until I noticed that a VM was 45 minutes off. I had 'Internet clock sync' active on the root (host), but apparently, the Windows Time Service is not very effective in fixing such a large drift. I would have to force a resync every 10 minutes or so to keep the clock within reasonable limits. I can workaround the whole problem but I would like to see a better Hyper-V in the future which doesn't have this problem.
regards,
Peter - Hi Jesper,
Thanks for your message. I can think of several workarounds, but since I couldn't find any good reason for the clock drift on the root, I wanted to address this issue in this forum.
regards,
Peter
