WinPE: Boot WIM’s Explained (The Physical)


Before getting too deep into updating WinPE for OS Deployments, it is important to know where all the Boot WIM’s are and what they are used for.  To keep this post simple, I will focus on x86 Boot WIM’s only.

AIK and ADK WinPE.wim

If you are using MDT, then you are certainly using AIK for Windows 7, or ADK for Windows 8.1 and Windows 10.  Before Importing an Operating System in MDT, the default Boot WIM used will be from the AIK or ADK installation directories.

On my Windows 8.1 x64 system, with ADK installed, the x86 Boot WIM is located at C:\Program Files (x86)\Windows Kits\8.1\Assessment and Deployment Kit\Windows Preinstallation Environment\x86\en-us\WinPE.wim.

A quick Dism Get-WimInfo will tell us all about this WIM

dism /Get-WimInfo /WimFile:"%WimFile%"

Index : 1
Name : Microsoft Windows PE (x86)
Description : Microsoft Windows PE (x86)
Size : 862,190,505 bytes

Here are all the file sizes for the WinPE.wim from AIK and ADK

  • WinPE 3 AIK x86 – 111,658 KB
  • WinPE 3 AIK x64 – 132,290 KB
  • WinPE 5 ADK x86 – 136,572 KB
  • WinPE 5 ADK x64 – 172,644 KB
  • WinPE 10 ADK x86 – 158,259 KB
  • WinPE 10 ADK x64 – 212,277 KB

These WIM’s are very lightweight and have minimal packages installed by default.

Boot.wim

The second WIM that we all know about is the Boot.wim.  This is found in the Sources directory of Operating System Media.  I’ll start with the sizes from the Enterprise editions.

  • WinPE 3 AIK x86 – 141,343 KB
  • WinPE 3 AIK x64 – 164,693 KB
  • WinPE 5 ADK x86 – 211,967 KB
  • WinPE 5 ADK x64 – 256,794 KB
  • WinPE 10 ADK x86 – 206,039 KB
  • WinPE 10 ADK x64 – 258,168 KB

As you can see they are quite a bit larger, but a quick check shows that there are actually two Indexes in this WIM.

dism /Get-WimInfo /WimFile:"%WimFile%"

Index : 1
Name : Microsoft Windows PE (x86)
Description : Microsoft Windows PE (x86)
Size : 975,806,531 bytes

Index : 2
Name : Microsoft Windows Setup (x86)
Description : Microsoft Windows Setup (x86)
Size : 1,055,849,199 bytes

Ok so this explains some of the size increase, but why two?

For starters, Index 2 is the Bootable wim and it is used when you boot to the DVD Media to install the OS.  Index 2 is also used by DaRT.  When importing an OS into MDT, Index 1 is used.

WinRE.wim

If you mount the Install.wim, you can find WinRE.wim in Windows\System32\Recovery.  Info on this WIM shows that this is actually the largest WIM, even though it is smaller than the Boot.wim (which has two indexes)

dism /Get-WimInfo /WimFile:"%WimFile%"

Index : 1
Name : Microsoft Windows Recovery Environment (x86)
Description : Microsoft Windows Recovery Environment (x86)
Size : 1,073,332,617 bytes
  • WinPE 3 AIK x86 – 141,882 KB
  • WinPE 3 AIK x64 – 165,249 KB
  • WinPE 5 ADK x86 – 202,950 KB
  • WinPE 5 ADK x64 – 246,755 KB
  • WinPE 10 ADK x86 – 232,644 KB
  • WinPE 10 ADK x64 – 295,712 KB

And now the physical comparison of the WinPE 5 x86 WIM’s.

Windows 8.1 ADK Boot.wim WinPE Boot.wim Setup WinRE.wim
Description Microsoft Windows PE (x86) Microsoft Windows PE (x86) Microsoft Windows Setup (x86) Microsoft Windows Recovery Environment (x86)
Size 133 MB 180 MB 190 MB 198 MB
Mounted Size 862,190,505 bytes 975,806,531 bytes 1,055,849,199 bytes 1,073,332,617 bytes

So what’s the real difference?

It all comes down to Features (dism /Get-Features) and Packages (dism /Get-Packages).  This will show what is actually installed in the WIM.  I recommend clicking on the image below.

7-27-2015 11-47-32 PM

So what does all this mean?

Well it depends on what you want to use WinPE for.  I’ll explain that in my next post.

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