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System.IO.DriveInfo[] allDrives = System.IO.DriveInfo.GetDrives();

            foreach (System.IO.DriveInfo d in allDrives)
            {
                Console.WriteLine("Drive {0}", d.Name);
                Console.WriteLine("  File type: {0}", d.DriveType);
                if (d.IsReady == true)
                {
                    Console.WriteLine("  Volume label: {0}", d.VolumeLabel);
                    Console.WriteLine("  File system: {0}", d.DriveFormat);
                    Console.WriteLine(
                        "  Available space to current user:{0, 15} bytes",
                        d.AvailableFreeSpace);

                    Console.WriteLine(
                        "  Total available space:          {0, 15} bytes",
                        d.TotalFreeSpace);

                    Console.WriteLine(
                        "  Total size of drive:            {0, 15} bytes ",
                        d.TotalSize);
                }
            }

            Console.ReadLine();					

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class Program
{
  private enum DriveType
  {
    unbekannt, 
    kein_Hauptverzeichnis, 
    Wechselmedium, 
    Festplatte, 
    Netzwerklaufwerk, 
    CD_DVD, 
    RAMDisk 
  }

  static void Main(string[] args)
  {  
    ConnectionOptions opt = new ConnectionOptions();
    ObjectQuery oQuery = new ObjectQuery("SELECT Size, FreeSpace, Name, FileSystem, DriveType " + 
                                         "FROM Win32_LogicalDisk");
  
    ManagementScope scope = new ManagementScope("\\\\localhost\\root\\cimv2", opt);
    ManagementObjectSearcher moSearcher = new ManagementObjectSearcher(scope, oQuery);
    ManagementObjectCollection collection = moSearcher.Get();

    foreach (ManagementObject res in collection)
    {
        decimal size = Convert.ToDecimal(res["Size"]) / 1024 / 1024 / 1024;
        decimal freeSpace = Convert.ToDecimal(res["FreeSpace"]) / 1024 / 1024 / 1024;

        Console.WriteLine(string.Format("Laufwerk: {0}", res["Name"]));
        Console.WriteLine(string.Format("LaufwerksTyp: {0}", Enum.GetName(typeof(DriveType), res["DriveType"])));
        Console.WriteLine(string.Format("Dateisystem: {0}", res["FileSystem"]));
        Console.WriteLine(string.Format("Laufwerksgröße: {0} GB", Decimal.Round(size, 2)));
        Console.WriteLine(string.Format("Freier Speicher: {0} GB", Decimal.Round(freeSpace, 2)));
        Console.WriteLine("-------------------------------------------------");
    }
    Console.ReadKey();
  }
}