Windows 10: Updates to WIM File Documentation and SHA-1 Usage in Lookup Tables

Hello,I have been reviewing the documentation related to the Windows Imaging Format WIM file and its internal structure, particularly the use of SHA-1 in the lookup table. I have a few questions that I’d like clarification on:Are there any updates to the official documentation regarding WIM files, specifically about the internal workings of the lookup table and hashing algorithms? refer documentation - https://www.microsoft.com/en-us/download/details.aspx?id=13096Could you elaborate on the significance of SHA-1 within the lookup table, such as why it was chosen and how it impacts ?Is there s

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Compacting a wim file?

Sorry, no idea where to put this. I just recently learned how to use dism. I use it to slipstream all hotfixes and ie10 ect into an AIO install disc. The problem is, it creates a huge install.wim after 8 index mounts and slipstreams. Considering all 8 images use the same darn wim and files, don't know why it has to increase the wim size by 1gig. Either I need to figure out how to use the same wim.install file for all indexes, or I need to compact the wim file which is now 4gbs with ie10 and all updates to April. Any way to do either?

 

Recover from WIM files.

Hello,Dusty_229

Welcome to Microsoft Community.

Restoring from a WIM file when the usual recovery options don't seem to work can indeed be a bit tricky, but I'm here to help guide you through an alternative method that might just do the trick. Since you've mentioned the WIM files can't be selected for restore in the usual way and the idea of using Command Prompt feels daunting, I'll break down the steps in a simple, easy-to-follow manner.

The goal here is to use the Deployment Image Servicing and Management (DISM) tool, which is a command-line tool that comes with Windows, to apply the image contained in the WIM file to your system. Here you can refer to this documentation | Append, apply, and export volume images with a Windows Image (.wim) file | Microsoft Learn

Before starting, make sure you have access to the Windows Recovery Environment (WinRE). and make a backup or copy of your WIM files, please see here to Boot into Windows Recovery Environment -<Windows Recovery Environment (Windows RE) | Microsoft Learn>

1. Once you're in the Windows Setup screen, click "Next."
   
2. Select "Repair your computer" at the bottom.
   
3. Go to "Troubleshoot" > "Advanced options" > "Command Prompt."
   

Now, you're going to use the DISM command to apply the WIM file to your system. You'll need to replace X: with the drive letter of your Windows installation (usually C:, but it might appear under a different letter in WinRE) and Y: with the drive letter of your USB drive where the WIM file is stored.

1. First, identify the correct drive letters for your system and USB drive by typing diskpart and then list volume in the Command Prompt. Look for the volume labeled "Windows" for your system drive and another for your USB drive. Exit DiskPart by typing exit.
   
2. Use the following DISM command to apply the image. Make sure to replace Y: with the actual drive letter of your USB drive and X: with the drive letter of your Windows installation:
   
   
   If your backup is split into multiple WIM files (like Reconstruct.WIM and Reconstruct.WIM2), you might need to apply the first part only, as DISM should automatically proceed with the next parts if they're named in sequence and located in the same folder.
   

->Final Steps

After the DISM command has successfully applied the WIM file:



You might need to repair the boot configuration data (BCD). You can do this with the following commands:

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Exit the Command Prompt and choose to "Continue" to boot to Windows normally, or restart your computer. you can run these commands in WinRE mode.

This process might seem a bit technical, but it's a powerful way to manually restore your system from a WIM file when other methods fail. If you feel uncertain at any step, don't hesitate to ask for further clarification.

Chandy |Microsoft Community Support Specialist

 

SHA-1 deprecation countdown

Source: SHA-1 deprecation countdown | Microsoft Edge Dev Blog