How to Restore a Snapshot (Full Snapshot Recovery)?

1. Prerequisites

• You must have access to the Azure snapshot resource.
• OSFMount installed on your machine.
• Administrator privileges to run PowerShell scripts.
  
  

2. Download Snapshot from Azure 

1.  Open the Azure Portal and navigate to the snapshot container and select a snapshot. 
   
2. Click Generate SAS on the top menu.
   - Set the expiry time as needed (default: 3600 seconds / 1 hour).
   - Click Generate SAS token and URL.
   - Copy the generated SAS URL.
   
3.  Download Snapshot 
    - Paste the SAS URL into a web browser; the snapshot download will start automatically.
   
   

              - Create a folder: C:\TestSnap
              - Copy the snapshot file into this folder
              - Rename the snapshot file to: snapshot.br
               

           4.  Decompress Snapshot 

           - Download Brotli from: https://github.com/google/brotli/releases
           - Use: Brotli-x64-windows-static.zip
           - Extract and place brotli.exe in C:\Brotli
           - Open Command Prompt and Run: C:\Brotli\brotli.exe -d snapshot.br
           - Snapshot file is decompressed successfully.
             

3. Install and Mount Snapshot Using OSFMount 

1. Download OSFMount from https://www.osforensics.com/tools/mount-disk-images.html.
   
2. Run the installer and follow the prompts to install OSFMount.
   
3. Launch OSFMount.
4. Click Mount New.
   
5. Select the downloaded snapshot file.
   
6. If multiple partitions appear, select the one containing your data.
7. Assign a drive letter (e.g., E:).
8. Check Read-only drive to avoid modifying the snapshot.
   
   
   
   
   
9. Click OK to mount the image.
10. Open File Explorer to verify the new drive is mounted successfully.
    
    

4. Restore the Entire Snapshot Script Configuration

1. Open PowerShell as Administrator.
2. Save the below script as Recover_Snapshot.ps1.
3. Update the configuration variables inside the script:

• $MountedDrive → specify the OSFMount drive letter (for example, E:)
• $DestinationDir → specify the folder where the recovered snapshot will be copied (for example, C:\RecoveredSnapshot)
• $SourceDir → specify the folder path inside the mounted snapshot to restore (for example, "$MountedDrive\FCGContainer\testalias")

       4.   Run the script:
                .\Recover_Snapshot.ps1

       5.   Upon successful execution, all files and folders from the mounted snapshot will be  restored to the destination directory you configured (for example, C:\RecoveredSnapshot).

5 .PowerShell Script – Recover Full Snapshot

# ==============================
# Restore Entire Snapshot 
# ==============================
# --- Configuration ---
$MountedDrive  = "E:" # OSFMount drive letter (mounted snapshot)
$SourceDir  = "$MountedDrive\FCGContainer\npbuild25vm" # Specific folder inside the snapshot to restore
$DestinationDir = "C:\RecoveredSnapshot" # Local recovery destination

Write-Host "`n=== Snapshot Restoration Process ===" -ForegroundColor Cyan
Write-Host "Mounted Drive  : $MountedDrive"
Write-Host "Source Folder  : $SourceDir"
Write-Host "Destination Dir : $DestinationDir"
Write-Host "----------------------------------------"

# --- Validate Source Folder ---
if (!(Test-Path $SourceDir)) {
Write-Host "Source folder '$SourceDir' not found in snapshot. Please verify the path." -ForegroundColor Red
exit
}

# --- Ensure destination folder exists ---
if (!(Test-Path $DestinationDir)) {
try {
New-Item -Path $DestinationDir -ItemType Directory -ErrorAction Stop | Out-Null
Write-Host "Created destination folder: $DestinationDir" -ForegroundColor Yellow
} catch {
Write-Host "Error creating destination folder: $($_.Exception.Message)" -ForegroundColor Red
exit
}
}

# --- Start Snapshot Restoration ---
Write-Host "`nRestoring snapshot from $SourceDir to $DestinationDir ..." -ForegroundColor Cyan

try {
$robocopyArgs = @(
('"' + $SourceDir + '"'),
('"' + $DestinationDir + '"'),
'/E',# Copy all subdirectories including empty ones
'/COPYALL',  # Preserve all attributes, timestamps, and permissions
'/R:2', # Retry twice on failure
'/W:5', # Wait 5 seconds between retries
'/NP',   # No progress display
'/NFL', # No file list
'/NDL'  # No directory list
  )

# Execute robocopy
$result = Start-Process -FilePath "robocopy.exe" -ArgumentList $robocopyArgs -Wait -NoNewWindow -PassThru

  # --- Evaluate Exit Code ---
    switch ($result.ExitCode) {
        {$_ -le 3} {
            Write-Host "`nSnapshot restoration completed successfully." -ForegroundColor Green
        }
        default {
            Write-Host "`nRestoration completed with issues. Exit code: $($result.ExitCode)" -ForegroundColor Yellow
            Write-Host "Snapshot restoration incomplete — please review the robocopy output for details." -ForegroundColor Yellow
        }
    }
}
catch {
    Write-Host "Snapshot restoration failed: $($_.Exception.Message)" -ForegroundColor Red
}

         

           

6. Note:

• To avoid PowerShell script execution restrictions, you may need to set the execution policy temporarily:

                      Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass

• Always mount the snapshot as read-only to avoid accidental changes.
• robocopy is used for robust and recursive folder copying preserving all metadata.
• If you encounter any permission issues, run PowerShell as Administrator