Windows 2011 SBS - Clock lags behind

[Tim-AtSharp]

Hi all,

I have a Proxmox 1.8 installation

Version (package/version/build)	pve-manager/1.8/5754
Kernel Version	Linux 2.6.32-4-pve #1 SMP Tue Mar 29 09:08:37 CEST 2011

It runs several VM's, and one of them is a Windows 2011 SBS server (64 bit), which is a domain controller. The problem is that the clock lags behind. The server is configured to sync with the microsoft NTP servers, which does it once a day. But after a few hours already, the clock starts lagging behind, until the next sync. I'm under the impression that the amount of lag is influenced by the server load. Since that server is a domain controller, it's time is replicated to all clients, so they have the wrong time too.

I read in the forum here that the VirtIO Network drivers might have something to dowith it, so I removed them. I'ce changed the NIC to a e1000, but the problem stays the same. To be sure, I've also changed the disk type to IDE, to completely avoid the VirtIO drivers, but no succes either.
I'm a bit puzzeled here... any solutions?
thanks!

 

[tom]

there are a lot of threads already about this topic, e.g. this one.
http://forum.proxmox.com/threads/5112-time-drift-in-all-guests?p=28971

as far as I know win 2011 sbs is based on win2008r2.

 

[TiagoRF]

We had those problems in all our installations of Proxmox, from 1.4 to 1.7, and failed to find a solution.

What we did however was, in all our domain controllers, use an "foreign" sntp software to sync everytime.

The other servers just query the DC for the current time, that stopped being an issue.

 

[tom]

do you enable USEPLATFORMCLOCK on your windows boxes?

I got good working setups with not using it (default in windows 2008r2) but the followings args in my /etc/qemu-server/VMID.conf file.

args: -no-hpet -no-kvm-pit-reinjection

Additional info:
I am using the latest virtio drivers for block and net, Kernel 2.6.32

 

[flow]

Do you use Virtio Network Drivers on your Windows VM?
After switching back to E1000 and installing the newest drivers from Intel my problem with lagging clocks under network load disappeared.

Virtio Block driver although seem to be fine.