Question

I am trying to modify a registry key that I have been told controls whether write-caching is enabled on particular hard drives. The key should be: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Enum\IDE\<DiskName>\<SerialNo>\Device Parameters\Disk\UserWriteCacheSetting

However I keep having problems when trying to create this key (as it doesn’t exist by default). If I try to open up the ...\Device Parameters\Disk\ with write access I get a SecurityException error; “Requested registry access is not allowed”. Now I have added the <requestedExecutionLevel level="requireAdministrator" uiAccess="false" /> flag to my manifest file so as to ensure I have admin access, but I’m still not having any luck.

Any ideas would be great!

    static void Main(string[] args)
    {
        RegistryKey myKey = Registry.LocalMachine.OpenSubKey("SYSTEM\\CurrentControlSet\\Enum\\IDE\\");

        foreach (string driveManafacturer in myKey.GetSubKeyNames())
        {
            RegistryKey driveKey = myKey.OpenSubKey(driveManafacturer);
            foreach (string driveID in driveKey.GetSubKeyNames())
            {
                RegistryKey driveIDKey = driveKey.OpenSubKey(driveID, true);
                string driveType = (string)driveIDKey.GetValue("Class");
                if (driveType == "DiskDrive")
                {
                    RegistryKey tempKey = driveIDKey.OpenSubKey("Device Parameters\\Disk\\", true);
                    if (tempKey == null)
                    {
                        tempKey = driveIDKey.CreateSubKey("Device Parameters\\Disk\\");
                        tempKey.SetValue("UserWriteCacheSetting", 0x0);
                    }
                }
            }
        }

        return;
    }

Answer 1

EDIT: Removed the idea about partial trust … it turned out that it had nothing to do with the problem.

I tried your code and got the same error – with some modifications it works:

RegistryKey myKey = Registry.LocalMachine.OpenSubKey( "SYSTEM\\CurrentControlSet\\Enum\\IDE\\" );

foreach( string driveManafacturer in myKey.GetSubKeyNames() )
{
  RegistryKey driveKey = myKey.OpenSubKey( driveManafacturer );

  foreach( string driveID in driveKey.GetSubKeyNames() )
  {
    RegistryKey subKey = driveKey.OpenSubKey( driveID );
    string driveType = (string)subKey.GetValue( "Class" );
    if( driveType == "DiskDrive" )
    {
      RegistryKey tempKey = subKey.OpenSubKey( "Device Parameters", true );
      RegistryKey tempKey2 = tempKey.OpenSubKey( "Disk" );
      if( tempKey2 == null )
      {
        tempKey2 = tempKey.CreateSubKey( "Disk" );
        tempKey2.SetValue( "UserWriteCacheSetting", 0x0 );
      }
    }
  }
}