Implementing a Windows 7 SteadyState by utilizing differencing VHDs files and the “Boot from VHD” feature

Update (07/July/2011): This solution is now deprecated. To get a vastly-improved Windows 7 SteadyState solution please visit this page: https://blogs.technet.com/b/panosm/archive/2011/07/07/windows-7-steadystate-solution-simplified.aspx

Windows SteadyState was a tool that allowed administrators to revert a workstation running XP or Vista to a previously stored state every time it reboots, or on administrator’s request. This feature was extremely useful in scenarios where workstation consistency at the OS and application level is required and the User State (user profile, user files, application settings) is not stored locally. Typical implementations of Windows SteadyState were workstation installations at schools, libraries or internet cafes. However, a recent trend that has been steadily increasing on the enterprise space is the need to deploy stable, rarely-updated machines that maintain their consistency across user sessions (boots) while improving manageability by utilizing Application Virtualization technologies as well as Group Policy. The end result is an Enterprise Workstation that is consistent, requires minimum management and costs less to maintain. You can find more info about Windows SteadyState at Wikipedia: https://en.wikipedia.org/wiki/Windows_SteadyState.

Windows SteadyState is now discontinued. The last supported operating system was Windows Vista and the version released for that OS (version 2.5) is incompatible with Windows 7. In it’s place Microsoft has released guidance on how to achieve a “SteadyState-like” functionality by using Group Policy (to restrict the level of changes that can be made to the OS by the end user) and MDT 2010 (to revert to a well-known initial condition). You can find more info here: https://technet.microsoft.com/en-us/library/gg176676(WS.10).aspx. Unfortunately using MDT 2010 to restore the OS to a well known initial state is sometimes not practical and can be time consuming.

A proposed alternative is the use of the a new Windows 7 feature called “Boot from VHD” or “Native VHD Boot”. This feature allows the usage of a VHD file (Virtual Hard Disk) to run the operating system instead of using a hard disk partition. It should not be confused with virtualization technologies like Hyper-V or Virtual PC. This feature does not use a hypervisor or virtual hardware. You should think of it as running your C: partition on a VHD file instead of a real hard disk partition. You can find more info about this feature here: https://technet.microsoft.com/en-us/library/dd440865(WS.10).aspx.

What is interesting about this feature is that it can work with a differencing VHD file. What is a differencing VHD file? A differencing VHD file is linked on a regular VHD file (called parent VHD) and only stores modified blocks of data in relation to its parent VHD. The result is that we can easily roll back changes by simply resetting this differencing VHD to its initial (empty) condition. This is a technique that is commonly used in Lab deployments where several virtual machines use differencing VHDs in order to test scenarios and then rollback changes. We can also use differencing disks to achieve the same result in a physical Windows 7 installation.

In this blog post we are going to describe a “step-by-step” guide on how to use this technique. In a second blog post we will describe how to automate the installation by using MDT 2010 so that we can leverage this capability at the enterprise level.

Step 1: Creating a WinPE ISO

WinPE is the Windows Preinstallation Environment used during the installation of Windows. It is also used for common maintenance tasks or for troubleshooting broken installations. It is included in Windows Automated Installation Kit for Windows 7 (Download). We will install and use WinPE in order to manage the differencing VHD of the Operating System either by discarding changes (to revert to our initial Steady State) or by committing the changes (by merging the differencing VHD to its parent VHD).

1. Download and install WAIK for Windows 7 (Link) on an existing Windows 7 or Windows Server 2008 R2 installation.

2. As Administrator run: Start –> All Programs –> Windows AIK –> Deployment Tools Command Prompt.

3. On the command prompt run the following commands:

   copype.cmd x86 c:\winpe_x86

   copy c:\winpe_x86\winpe.wim c:\winpe_x86\ISO\sources\boot.wim

   copy "c:\program files\Windows AIK\Tools\x86\ImageX.exe" c:\winpe_x86\iso\

   copy c:\windows\system32\bcdedit.exe c:\winpe_x86\iso\

   oscdimg.exe –bC:\winpe_x86\iso\boot\etfsboot.com –u2 –h -m -lWINPE C:\winpe_x86\iso\ C:\WINPE.iso(Note: Replace x86 with x64 if you are looking to install the x64 version of Windows 7)

4. Store the resulting WINPE.iso file. We will use it to install WinPE on our workstation later.

Step 2: Creating the VHD files

On Step 2 we are going to use the diskpart command line utility to format the physical hard disk and create 3 VHD files:

• c:\win7.vhd: The parent VHD file which will contain our “Steady State”.
• c:\temp.vhd: The differencing VHD file which will be used to store the changes.
• c:\winpe.vhd: The VHD file which will host WinPE.

The command below will create a parent VHD file of approximately 30 GB size and of type “expandable” (meaning that it will start from zero size and expand up to the 30 GB limit). Feel free to change the size according to your specifications. You can also use a type “fixed” vhd file which will pre-allocate the whole size of the VHD (by creating a big VHD file of the maximum size you specify). Using a “fixed” VHD file will give you a small performance improvement vs. using an “expandable” one. The last step will create a copy of the differencing VHD which we will use to quick revert our VHD to an initial “empty” state.

1. On the target workstation boot from your Windows 7 media.

2. On the Setup Screen click SHIFT-F10 to open the command prompt.

3. On the command prompt run the following commands:

   diskpart

   select disk 0

   clean

   create partition primary

   select partition 1

   active

   format fs=ntfs quick

   assign letter=C

   create vdisk file=”c:\win7.vhd” maximum=30000 type=expandable

   create vdisk file=”c:\temp.vhd” parent=”c:\win7.vhd”

   create vdisk file=”c:\winpe.vhd” maximum=2000 type=expandable

   select vdisk file=”c:\win7.vhd”

   attach vdisk

   exit

   copy c:\temp.vhd c:\temp.vhd.orig

Step 3: Installing Windows 7 on the parent VHD file

The next step is to use the win7.vhd file we created, to install Windows 7:

1. Close the command prompt and return to the Windows 7 setup. Click “Next” and proceed with the installation by selecting “Install Now”.

2. Select “Custom (Advanced)” installation.

3. Select the VHD file to install Windows 7 (you will notice which one it is by its size, in comparison to the physical hard disk).

   

4. Ignore the error “Windows cannot be installed to this disk.” and proceed with the setup by clicking “Next”.

5. Complete the OS setup and logon to your new Windows 7 installation.

Step 4: Installing WinPE on the winpe.vhd file

On your new Windows 7 installation perform the following to install WinPE on the winpe.vhd file.

1. Open the Command Prompt as Administrator.

2. Run the command:

   bcdedit –copy {current} /d “Windows 7 AVHD”

   This command will return a GUID in the form of {94bb083f-1f8f-11e0-8b9f-a1bc155f31e3}. Make a note of this GUID as you will use it in the commands that follow and also during Step 5. This is the GUID for the differencing VHD.

3. Run the commands:

   bcdedit –set GUID device vhd=[D:]\temp.vhd

   bcdedit –set GUID osdevice vhd=[D:]\temp.vhd

   Replace GUID with the one that you got from the bcdedit –copy command previously.
   Replace D: with the drive where your temp.vhd is located (if it is not on D:). Do not omit the brackets!

4. Run the following commands to format winpe.vhd and install WinPE in it:

   diskpart

   select vdisk file=”d:\winpe.vhd”

   attach vdisk

   clean

   create partition primary

   format fs=ntfs quick

   assign letter p

   exit

5. Insert the WINPE.iso you created on Step 1. Let’s say that you inserted it on E: (replace accordingly below – if different).

6. Run the commands:

   e:\imagex /apply e:\sources\boot.wim 1 p:

   xcopy e:\boot\*.* /e /f p:\boot\

   copy e:\bootmgr p:

   bcdedit -create /d "WinPE" -application osloader

   The last command will return a GUID in the form of {94bb083f-1f8f-11e0-8b9f-a1bc155f31e3}. Make a note of this GUID as you will use it in the commands that follow. This is the GUID for WinPE.

7. Run the commands:

   bcdedit -set GUID device vhd=[D:]\winpe.vhd

   bcdedit -set GUID osdevice vhd=[D:]\winpe.vhd

   bcdedit -set GUID path \windows\system32\boot\winload.exe

   bcdedit –set GUID systemroot \windows

   bcdedit -set GUID winpe yes

   bcdedit -set GUID nx OptIn

   bcdedit -set GUID detecthal yes

   bcdedit -displayorder GUID –addlast

   bcdedit -timeout 0

   Replace GUID with the one that you got from the bcdedit –create command.
   Replace D: with the drive where your winpe.vhd is located (if it is not on D:). Do not omit the brackets!

Step 5: Create the scripts to automate discarding and committing changes

We have created all the necessary VHD files. In the next step we need to provide the logic behind “discarding” and “committing” changes we have made in each session. As previously explained this is done by either resetting or merging the differencing VHD file temp.vhd. This procedure is done by booting into WinPE (through winpe.vhd which we created in Step 4), doing the change, and then rebooting to the differencing VHD. There are two options that we will configure:

• Discard the changes and revert to the “SteadyState”: This is done by simply rebooting or shutting down and restart the machine. We will place a script running during the shutdown which will configure an autorun script for WinPE to delete temp.vhd, replace it with a blank one and then change the default booting partition to the (now empty) differencing VHD (temp.vhd).
• Commit the changes permanently: This is done by running a script located in c:\windows\system32 called Commit.Bat. This script configures an autorun script for WinPE to merge temp.vhd with win7.vhd, create a new empty temp.vhd differencing disk and then change the default booting partition to the (now empty) differencing VHD (temp.vhd).

Additionally we will also configure a startup command to change the default booting partition to WinPE (winpe.vhd).

Here are the detailed steps on how to configure this:

1. First of we need two things: The 2 GUIDs we used during Step 4, the differencing VHD GUID and the WinPE GUID. We are going to use those to define the default booting partition (this is how bcdedit works).

2. Run: gpedit.msc to open to Local Group Policy Editor. Go to: Local Computer Policy –> Computer Configuration –> Windows Settings –> Scripts (Startup/Shutdown). Double-Click “Startup” to open the “Startup Properties” window and click “Add”. Enter the following:

   Script Name: c:\windows\system32\bcdedit.exe
   Script Parameters: –default GUID

   Replace GUID above with the WinPE GUID you noted in Step 4. Click “OK” and close Local Group Policy Editor.

   

3. Verify that winpe.vhd is still mounted as Drive P:. If this is not the case then use diskpart (or diskmgmt.msc) to attach it.

4. Go to: P:\windows\system32 and run:

   notepad winpeshl.ini

5. Add the following lines inside winpeshl.ini:

   [LaunchApps]
   %SYSTEMROOT%\system32\winpe.bat

   This file will autorun winpe.bat during WinPE boot. After completion WinPE will automatically reboot the computer. Save the file and close Notepad.

6. Again from: P:\windows\system32 run:

   notepad discard.bat

7. Add the following lines inside discard.bat:

   copy /y c:\temp.vhd.orig c:\temp.vhd

   bcdedit –default GUID

   Where GUID is the differencing VHD GUID you noted in Step 4. Save the file and close Notepad.

8. Again from: P:\windows\system32 run:

   notepad commit.bat

9. Add the following lines inside commit.bat:

   echo select vdisk file=c:\temp.vhd > vhdmerge.s

   echo merge vdisk depth=1 >> vhdmerge.s

   diskpart –s vhdmerge.s

   copy /y c:\temp.vhd.orig c:\temp.vhd

   bcdedit –default GUID

   copy /y discard.bat winpe.bat

   Where GUID is the differencing VHD GUID you noted in Step 4. Save the file and close Notepad.

10. Again from: P:\windows\system32\ run:

    copy discard.bat winpe.bat

11. Create a new bat file on c:\windows\system32 called commit.bat. In it add the following lines:

    echo select vdisk file=D:\winpe.vhd > winpe.s

    echo attach vdisk >> winpe.s

    diskpart –s winpe.s

    ping 127.0.0.1

    copy /y p:\windows\system32\commit.bat p:\windows\system32\winpe.bat

    Where D: is the drive where your VHD is stored. Save the file.

12. From the command prompt execute the following command:

    bcdedit –default GUID

    Where GUID is the WinPE GUID you noted in Step 4.

That’s it! You can proceed to configure Windows 7 exactly the way you want to appear in your initial “SteadyState” (even Windows Activation will work between sessions). Each time you restart WinPE will run and discard all the changes by resetting the differencing VHD and then reboot to Windows 7.

If you want to commit the changes you have made then you need to run: c:\windows\system32\commit.bat (of course as a local administrator!) and the changes will stay as WinPE will merge the differencing VHD to its parent after the first reboot.

Below is a flow chart detailing the procedure:

In a next blog post I will outline how you can automate this procedure by using MDT 2010 (Microsoft Deployment Toolkit) and AutoIT scripts.

Feel free to provide feedback on ways to improve this implementation either by contacting me or by commenting below.

Thanks,

Panos Macheras
Infrastructure Consultant

Comments

• Anonymous
  January 01, 2003
  Thanks for this great write up, it is exactly what we needed. I was wondering though, is there a way to commit the Windows Updates that get installed when shutting down? When I run those kind of large updates, I can't seem to figure out how to get them to stay. Thanks

• Anonymous
  January 01, 2003
  First of all, a huge "thank you" for taking the time to comment! Wilson: I don't have access to the product group so it's hard to say. My guess is that it won't happen as there has to be a differentiator between the various editions. Kalagan75: Just make sure that you run commit.bat each time you login to windows and before you start the setup. If the software automatically restarts the OS then your changes will persist between reboots. If the software reboots the OS automatically twice then add the commit.bat command to the startup script section of the Local Group Policy (through gpedit.msc), complete the setup, and then remove it. Lukas: I have received tons of requests to automate this as (understandably) people find the procedure too cumbersome to follow on more than 3-4 pcs. Stay tuned! I am working on fully automating this and will (hopefully) have a new blog post in the next 3-4 weeks. Regarding cloning: Yes, you can do it (I have) but the trick is to create a SYSPREP-ed initial VHD file (instead of just installing Win7 to it). The automated procedure that I am working on will be deployable to several pcs. Of course, this does not bypass activation (it still needs to be done separately on each pc) but it creates unique GUIDs and is generally the ONLY supported way to "clone" images to similar hardware. Stormer: Thank you for your kind words. I am sure you will find the automated procedure (coming soon on a new blog post) to be of much more help. Shekhar: Glad to be of service. The next blog post (coming in the next 3-4 weeks hopefully) will detail exactly what you are looking for. Stay tuned! :-)

• Anonymous
  January 28, 2011
  Will Microsoft consider releax requirement on native boot from a VHD in Winodws 7? This feature require Windows 7 Ultimate and doesn't work in Windows 7 Professional.

• Anonymous
  February 18, 2011
  Wow, it's exactly what I need. Just a thing: if I need to retain changes for one or more restart? (for example if I need to test a software that requires a reboot) Thanks in advance

• Anonymous
  March 02, 2011
  It looks amazing. Quite difficult to set up, but it seems that it can be working good in shared computer environment. When you release next blog post about automating this procedure? Thanks

• Anonymous
  March 02, 2011
  I have question. If I prepare workstation like this, can I clone this workstation and use this SteadyState-like functionality in all cloned computers? I am doing clones with Acronis True Image and I know, that after cloning I have to activate Windows at each cloned Workstation even if stations are the same. So I am little bit worried about GUIDs - I suppose they are unique for each computer, so after cloning, will it work or not? Thanks

• Anonymous
  March 05, 2011
  Thanks for this great blog post! I followed your steps and got myself a very nice setup, where changes are reverted by default. More importantly, if I decide to commit the changes, they will be merged to the parent. Very nice.

• Anonymous
  March 08, 2011
  Awsome !!!  you helped me out big time. We were planning to use Windows 7/XP to create a Thin OS  to allow RDP/3rd party utility to connect to connection servers . I preferred Windows 7 as i has inbuilt support for 99 % of older hardware, on which it is intended to run. Just having issues when Ghosting/Wim imaging the Clone to multiple HDD. We plan to have the ThinOS imaged to multiple HDD's at the same time. Somehow the BCD store is getting messed up on applying the Clone. just was wondering, is it possible to incorporate a Autoattended Sysprep to ensure all machines have unique SID ? These clones are going to work standaone, no domain membership/.

• Anonymous
  March 15, 2011
  A few years ago I created a free tool called Wioski. It will do the same: http://www.wioski.com/ The result is the same though the approach a bit different. Check it out! Thanks for a good step by step :)

• Anonymous
  July 28, 2011
  I am having the same issue as Shekhar and wanted to know if you came up with a solution?

• Anonymous
  April 17, 2012
  I figured it out a while ago so I thought I would update.  You need to run gpedit.msc and browse to Local Computer Policy -> Computer Configuration -> Windows Settings -> Scripts (Startup/Shutdown). Double-click Startup, click Add, browse to C:WindowsSystem32commit.bat, and click OK. Repeat this for Shutdown. After you are finished these Group Policy entries must be removed. After these scripts are removed, commit.bat needs to be run again so the scripts don't come back after a reboot.

• Anonymous
  December 19, 2012
  Hello the forum, Please, just a question :

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Step 2: Creating the VHD files

1. On the target workstation boot from your Windows 7 media

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About the target workstation, it's a PC with Windows 7 installed or an empty PC without any system ? Cordially, Hafid.