请使用“大小”和“自由”函数解决此问题。ComboBox1包含驱动器号列表。

var
  Disk: Integer;
...
procedure TForm1.Button1Click(Sender: TObject);
var
  Total, Free: LongInt;
begin
  Total:=DiskSize(Disk) div 1024;
  Free:=DiskFree(Disk) div 1024;
  Gauge1.MaxValue:=Total;
  Gauge1.Progress:=Free;
  Label1.Caption:='Total size - '+IntToStr(Total);
  Label2.Caption:='Free - '+IntToStr(Free);
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
begin
  Disk:=ComboBox1.ItemIndex+1;
end;

在这里，您可以使用Win32_LogicalDisk xml2类进行另一种选择

{$APPTYPE CONSOLE}

uses
  SysUtils,
  ActiveX,
  ComObj,
  Variants;

procedure  GetWin32_LogicalDiskSize(const drive: string);
const
  WbemUser            ='';
  WbemPassword        ='';
  WbemComputer        ='localhost';
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer(WbemComputer, 'root\CIMV2', WbemUser, WbemPassword);
  FWbemObjectSet:= FWMIService.ExecQuery(Format('SELECT * FROM Win32_LogicalDisk Where Caption=%s',[QuotedStr(drive)]),'WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  if oEnum.Next(1, FWbemObject, iValue) = 0 then
  begin
    Writeln(Format('FreeSpace  %s Bytes',[FormatFloat('#,',FWbemObject.FreeSpace)]));// Uint64
    Writeln(Format('Size       %s Bytes',[FormatFloat('#,',FWbemObject.Size)]));// Uint64
    FWbemObject:=Unassigned;
  end;
end;

begin
 try
    CoInitialize(nil);
    try
      GetWin32_LogicalDiskSize('C:');
    finally
      CoUninitialize;
    end;
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;
end.

有些人可能会发现这很有用-它将给予您的总和自由磁盘空间的卷的设备ID。它也使用类似于RRUZ的应答，但它与DeviceID一起工作，因此它具有相同的优点+它也与未Map的设备和驱动程序（或Map到路径）一起工作。

procedure DiskSizesFromVolumeDeviceID(deviceID:string);
var
  WMIServices : ISWbemServices;
  Root        : ISWbemObjectSet;
  Item: Variant;
  i: Integer;
  Cap:TCap;
begin
  try
  WMIServices := CoSWbemLocator.Create.ConnectServer('.', 'root\cimv2','', '', '', '', 0,     nil);
  Root  := WMIServices.ExecQuery(Format('SELECT Capacity, FreeSpace FROM Win32_Volume     WHERE DeviceID="%s"', [StringReplace(deviceID, '\', '\\', [rfReplaceAll])]),'WQL', 0, nil);
  for i := 0 to Root.Count - 1 do
  begin
    Item := Root.ItemIndex(i);

    TotalSpace := ( Item.Capacity);
    FreeSpace := (Item.FreeSpace);
  End;
end;

使用此代码的最佳方法：

var
    lpFreeBytesAvailableToCaller, 
    lpTotalNumberOfBytes, 
    lpTotalNumberOfFreeBytes : TLargeInteger; // Int64;
begin
   ...
   GetDiskFreeSpaceExA(PChar(path_to_dir), lpFreeBytesAvailableToCaller, lpTotalNumberOfBytes, @lpTotalNumberOfFreeBytes);
   ...
end;