Tag Archives: Hotfix

Déjà vu Bug: The network connection of a running Hyper-V virtual machine may be lost under heavy outgoing network traffic on a computer that is running Windows Server 2008 R2 SP1

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Anyone who’s been doing virtualization with Hyper-V on Windows 2008 R2 has a good change of having seen the issue described in http://support.microsoft.com/kb/974909/en-us

You install the Hyper-V role on a computer that is running Windows Server 2008 R2.

  • You run a virtual machine on the computer.
  • You use a network adapter on the virtual machine to access a network.
  • You establish many concurrent network connections, or there is heavy outgoing network traffic.

In this scenario, the network connection on the virtual machine may be lost. Additionally, the network adapter is disabled.
Note You have to restart the virtual machine to recover from this issue.

We’ve seen this one on VM’s that have indeed a lot of outgoing traffic.  In our environment the situation looks like this:

  • You can access the VM with Hyper-V Manager or SCVMM but not via RDP as all Network connectivity is lost.  The status the  guest NIS is always “Enabled” but there is no traffic/connectivity
  • You can try to disable the NIC but this tales a  very long time and when you try to enable it again this never succeeds. Disconnecting the NIC form the virtual network and connecting it again doesn’t help either.
  • You need to shut down the host but this takes an extremely long time, so long you really can’t afford to wait if it ever succeeds. It seems to hang at shutting down with a “non whirling whirly”.  So finally you’ll power off the VM and start it up again. Apart from entries related to having not connectivity the event logs are “clean” and there is no indication as to what happened.

Well this exact same issue is back with Windows 2008 R2 SP1. That’s the bad news. The good news is there is a hotfix for it already so you can fix it. You can read up on this issue in Knowledge Base article 2263829  and request the hotfix here. Instructions to get the hotfix are in there as well as a reference to the previous fixes for Windows 2008 R2 RTM.

Consider the following scenario:

  • You install the Hyper-V role on a computer that is running Windows Server 2008 R2 Service Pack 1 (SP1).
  • You run a virtual machine on the computer.
  • You use a network adapter on the virtual machine to access a network.
  • You establish many concurrent network connections. Or, there is heavy outgoing network traffic.

In this scenario, the network connection on the virtual machine may be lost. Additionally, the network adapter may be disabled.
Notes

  • You must restart the virtual machine to recover from this issue.
  • This issue can also occur on versions of Windows Server 2008 R2 that do not have SP1 installed. To resolve the issue, apply the hotfix that is described in one of the following Microsoft Knowledge Base articles:

    974909 (http://support.microsoft.com/kb/974909/ ) The network connection of a running Hyper-V virtual machine is lost under heavy outgoing network traffic on a Windows Server 2008 R2-based computer
    2264080 (http://support.microsoft.com/kb/2264080/ ) An update rollup package for the Hyper-V role in Windows Server 2008 R2: August 24, 2010

Oh yeah, people often seem confused  as to where to install the hotfix. Does it go on the Hyper-V hosts or and/or on the guest?  It’s a hyper visor bug in Hyper-V so it goes on the hosts. Have a nice weekend.

KB2230887 Hotfix for Dynamic Memory with Windows 2008 Standard & Web edition does not apply to without Hyper-V editions?

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As my readers all know by now, since I blogged about this here, you need to install an update/hotfix for Hyper-v Dynamic Memory to work with Windows 2008 Standard & Web edition. You can find more information here:  Hyper-V Dynamic Memory does not work on a Windows Server 2008 Standard Edition or Windows Web Server 2008 virtual machine (VM)

UPDATE 2011/06/23: Microsoft released the hotfix based on end-user feedback and you can download version 2 that works on all SKUs now http://support.microsoft.com/kb/2230887 (v2).

The cause is that on these versions of the operating systems the the required memory enlightenment is supported. After installing the hotfix (or SP1 in the case of Windows 2008 R2) memory addition enlightenment is available on these SKU and your good to go.

But recently I ran into an issue. One virtual machine guest on a Windows 2008 R2 SP1 cluster that is running the Windows 2008 Standard edition without Hyper-V SKU, x86 the standalone installer for Windows6.0-KB2230887-x86 throws following warning:

Windows Update Standalone Installer

The update does not apply to your system

OK

That’s a bit strange. As you can see the hotfix has not been installed. And why would I need the with Hyper-V SKU to use dynamic memory with this guest?

I installed the same hotfix without any issue on several Windows 2008 Standard Edition (the SKU with Hyper-V)  guests. So what is going on here? What exactly is different about the without Hyper-V SKU?  Note that Windows 2008 R2 no longer has such a SKU.  Microsoft states that it is an SKU for people who don’t need virtualization. Well as they installed it as a guest virtual machine they chose this version and now what? No hotfix for dynamic memory as a guest?

There is a TechNet forum discussion going on here where they have this issue and I asked them to check what SKU it was happening on. Bingo! It’s on the Windows 2008 Standard without Hyper-V version!

I don’t expect any Hyper-V functionality or management tools but I do expect to get the hotfix to enable Dynamic Memory in guests with this SKU, just like we get any other update that is relevant to Hyper-V, for example, upgraded Integration Services. I’m going to ping a Microsoft contact on this one and see if they can help with this. And in case you’re wondering SKU = Stock Keeping Unit.