Category Archives: Virtualization

How to tell if your CPU Supports SLAT

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SLAT-enabled processor is the requirement of Hyper-V RemoteFX feature which is introduced in Windows Server 2008 R2. It’s the requirement of Windows 8 client Hpyer-V feature as well.

For INTEL CPU models, following CPU models are SLAT-Capable

  • Server: E5500 or higher.
  • Desktop/Laptops: I3/I5/I7/I7-qm

There is a handy tool named CoreInfo from systeminternals that can check if your CPU is SLAT-Capable, it’s pretty easy to use:

  1. Download from http://technet.microsoft.com/en-us/sysinternals/cc835722
  2. Launch an elevated command prompt
  3. Run “CoreInfo.exe -v”

If you see EPT  Supports Intel extended page tables (SLAT) then you are good.

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References:

Hyper-V: List of SLAT-Capable CPUs for Hosts

Understanding High-End Video Performance Issues with Hyper-V

Hyper-v Tip: Use windows key without fullscreen

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When connect to a remote VM with hyper-v manager, I have to full screen to make Windows key. Personally I think Hyper-V should have a Windows key button in toolbar like "Ctrl+Alt+Delete" button.

Actually Hyper-v manager allows you to select where the Windows keys goes when you press it. Open up the Hyper-V Settings dialog from with the Hyper-V Manager and go to the keyboard setting, you will see 3 settings.

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  1. Use on the physical computer
  2. Use on the virtual machine
  3. Use on the virtual machine only when running full-screen

The default one is #3. Once you change it to #2, you will be able to use Windows key inside VM without *full-screen* it.

You will find this helpful if you are connecting to a VM has Windows 8 Metro UI enabled. Without a windows key it’s hard to exit Metro style app and go back to start screen.

How to turn on client hyper-v in Windows 8

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In Steven Sinofsky’s this blog – Bringing Hyper-V to “Windows 8”. He talks about that Windows 8 will support virtualization on the "client" OS.  This is very helpful for developers as they typically have the need to setup additional test environment on their PC.

How to turn on client hyper-v in Windows 8

First, make sure your system meets the client hyper-v virtualization requirement, you have 64bit windows 8 OS and SLAT available on CPU.

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  1. Control Panel –> Programs
  2. Turn Windows Features On or Off
  3. Check Hyper-V, Click Ok

Note: If your system does not have the required virtualization support, the client Hyper-V feature will be greyed out. To check if your CPU is SLAT-capable, check this How to tell if your CPU Supports SLAT.

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The other cool thing is you can turn hyper-v on even if you are booting from VHD. This behavior is same server Hyper-V in Windows Server 2008 R2.

Using SCVMM 2012 Cmdlets in PowerShell

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SCVMM Cmdlets allow SCVMM admin/users to do everything they can do in SCVMM AdminConsole in windows PowerShell command line. In SCVMM 2008 R2, you can run following command in PowerShell to run SCVMM cmdlets.

Add-PSSnapin Microsoft.SystemCenter.VirtualMachineManager

But this does not work in SCVMM 2012 as SCVMM 2012 uses PowerShell module. For SCVMM 2012 now you need run following in PowerShell instead

Import-Module "C:\Program Files\Microsoft System Center 2012\Virtual Machine Manager\bin\psModules\virtualmachinemanager\virtualmachinemanager"

(This assumes that you have SCVMM 2012 installed on the default location C:\Program Files\Microsoft System Center 2012 )

The PowerShell cmdlets in SCVMM 2012 change a lot in SCVMM 2012, you can get a list of all SCVMM 2012 cmdlets by typing the following at the PowerShell command shell prompt

Get-Command -Module virtualmachinemanager -Type cmdlet

And you can run Get-Help on any of the cmdlets to get the syntax for that cmdlet.

Get-Help <cmdlet name> -detailed

Update: Microsoft has published the SCVMM 2012 cmdlets help to TechNet, check it out http://technet.microsoft.com/en-us/library/hh801697.aspx

Improve VM deploy performance in SCVMM

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SCVMM use BITS over https to deploy virtual machine to host server. To improve the performance of virtual machine deploy, you can disable encrypted file transfers for Host Group.

  1. Open Virtual Machine Manager Administrator Console (aka SCVMM Console) on the Application Tier and connect to VMM Server
  2. Click Host on the left side pane.
  3. Right Click on All Host node, and select Properties.
  4. Select the check-box “Allow unencrypted file transfers”

Note: if you use library server, you should set Allow unencrypted file transfers for every library servers.

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The same can be done in following SCVMM PowerShell command

Set-VMHostGroup -VMHostGroup “All Hosts” -AllowUnencryptedTransfers $true

IDE/ATAPI Account does not have sufficient privilege to open attachment

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You might get following error after you move or replace a virtual disk drive file of a hyper-v virtual machine.

An error occurred while attempting to start the selected virtual machine(s).
‘TestVM’ failed to start.
Microsoft Emulated IDE Controller (Instance ID
{83F8638B-8DCA-4152-9EDA-2CA8B33039B4}): Failed to Power on with Error ‘General
access denied error’
IDE/ATAPI Account does not have sufficient privilege to open attachment
‘D:\VM\TestVM\TestVM.vhd. Error: ‘General access denied error’
Account does not have sufficient privilege to open attachment
‘D:\VM\TestVM\TestVM.vhd. Error: ‘General access denied error’

This is because the permissions on the new virtual hard drive (D:\VM\TestVM\TestVM.vhd in this case) are incorrect. Here is the steps to fix this permission file.

  1. Open Hyper-V manager, Right click settings of the virtual machine,
  2. Find the Virtual Hard Drive and choose "Remove".
  3. Re-add the same Virtual Hard Drive back to the machine.
  4. Now start the VM again, it should boot successfully.

Could not load file or assembly TraceWrapper, Version=1.0.523.0

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There are two versions of the TraceWrapper.dll in SCVMM install CD. One is x86 version and the other is x64 version. When you build your application on top of SCVMM library Microsoft.SystemCenter.VirtualMachineManager, it’s very important to pick up the correct version TraceWrapper.dll. In general, you should copy the 32 bit dll if you are using 32 bit system, copy 64 bit dll if you are using 64 bit system. Otherwise following BadImageFormatException would occur during runtime.

Could not load file or assembly ‘TraceWrapper, Version=1.0.523.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35′ or one of its dependencies. An attempt was made to load a program with an incorrect format.

However, you should keep using 32 bit TraceWrapper on a 64 bit system for following scenarios:

  • You need debug your app in Visual Studio directly. In this case, process launched from Visual Studio debugger runs in WOW64 mode.
  • IIS is configured to run in 32 bit mode. In this case, all working processes run in WOW64 mode.

This is because in 64 bit windows, processes in WOW64 mode are 32 bit processes and can’t load 64 bit TraceWrapper.dll.

Install Remote Server Administration Tools on Windows 7 SP1

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Remote Server Administrator Tools (RSAT) is not compatible with Windows 7 SP1. If you install Remote Server Administration Tools on Windows 7 SP1 slipstreamed media, you will get following error.

The update is not applicable to your computer

That’s because current RSAT version only supports Windows 7 RTM. To workaround this issue, you can Install Remote Server Administration Tools before installing Windows 7 SP1. The SP1 upgrade will update RSAT to SP1 version. The other option is wait for official release of Remote Server Administrator Tools for windows 7 SP1, which will happen this April.

Update 4/8/2011: Microsoft released Windows 7 SP1 RSAT Tools to public today. The download link is here http://www.microsoft.com/downloads/en/details.aspx?FamilyID=7d2f6ad7-656b-4313-a005-4e344e43997d