type

  TScalarPrefetch = record

    Minimum: Word;

    Maximum: Word;

    MaximumBlocks: Word;

  end;

 

  TBlockPrefetch = record

    Minimum: Word;

    Maximum: Word;

  end;

 

  DISK_CACHE_RETENTION_PRIORITY = (EqualPriority, KeepPrefetchedData, KeepReadData);

  TDiskCacheRetentionPriority = DISK_CACHE_RETENTION_PRIORITY;

 

  _DISK_CACHE_INFORMATION = record

    ParametersSavable: Boolean;

    ReadCacheEnabled: Boolean;

    WriteCacheEnabled: Boolean;

    ReadRetentionPriority: DISK_CACHE_RETENTION_PRIORITY;

    WriteRetentionPriority: DISK_CACHE_RETENTION_PRIORITY;

    DisablePrefetchTransferLength: Word;

    PrefetchScalar: Bool;

    ScalarPrefetch: TScalarPrefetch;

    BlockPrefetch: TBlockPrefetch;

  end;

  DISK_CACHE_INFORMATION = _DISK_CACHE_INFORMATION;

  TDiskCacheInformation = DISK_CACHE_INFORMATION;

 

const

 IOCTL_DISK_GET_CACHE_INFORMATION = {text}0740D4;

 IOCTL_DISK_SET_CACHE_INFORMATION = {text}07C0D8;

 IOCTL_DISK_SET_CACHE_SETTING     = {text}07c0e4;

 IOCTL_DISK_GET_LENGTH_INFO       = {text}07405C;

 

procedure TForm1.Button2Click(Sender: TObject);

var

  h: THandle;

  info: TDiskCacheInformation;

  response: DWord;

  E: Integer;

begin

  h := CreateFile(PChar('\.\D:'), GENERIC_READ or GENERIC_WRITE, FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, FILE_ATTRIBUTE_SYSTEM, 0);

  if h = INVALID_HANDLE_VALUE then begin

    ShowMessage('Can''t access disk.');

    Exit;

  end;

 

  info.WriteCacheEnabled := True;

  info.ReadCacheEnabled:= false;

  info.DisablePrefetchTransferLength := 1;

 if not DeviceIoControl(h, IOCTL_DISK_SET_CACHE_INFORMATION, nil, 0, @info, SizeOf(info), response, nil) then begin

    E:=GetLastError;

    Showmessage(Format('Error: %d', [E])); //ERROR 24

    Exit;

  end;

 

 CloseHandle(h);

end;