C# Signature:

[DllImport("Kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
extern static bool GetVolumeInformation(
  string RootPathName,
  StringBuilder VolumeNameBuffer,
  int VolumeNameSize,
  out uint VolumeSerialNumber,
  out uint MaximumComponentLength,
  out uint FileSystemFlags,
  StringBuilder FileSystemNameBuffer,
  int nFileSystemNameSize);

VB Signature:

  <System.Runtime.InteropServices.DllImport("Kernel32.dll", CharSet:=System.Runtime.InteropServices.CharSet.Auto, SetLastError:=True)> _
  Public Shared Function GetVolumeInformation(ByVal RootPathName As String, ByVal VolumeNameBuffer As System.Text.StringBuilder, ByVal VolumeNameSize As Int32, ByRef VolumeSerialNumber As Int32, ByRef MaximumComponentLength As Int32, ByRef FileSystemFlags As Int32, ByVal FileSystemNameBuffer As System.Text.StringBuilder, ByVal nFileSystemNameSize As Int32) As Boolean
  End Function

User-Defined Types:

None.

Notes:

The VolumeSerialNumber is not optional with this signature!!!

Tips & Tricks:

If you specify RootPathName as a driveletter (eg not a volume name) then you have to terminate it with a backslash.

I had to change the return type to int and compare with 0. The bool return value didn't work for me.

Adding the attribute [return: MarshalAs(UnmanagedType.Bool)] should make the bool return value work.

Sample Code:

StringBuilder volname = new StringBuilder(256);
StringBuilder fsname = new StringBuilder(256);
uint sernum, maxlen, flags;
if(!GetVolumeInformation("c:\\", volname, volname.Capacity, out sernum, out maxlen, out flags, fsname, fsname.Capacity))
    Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
string volnamestr = volname.ToString();
string fsnamestr = fsname.ToString();

Alternative Managed API:

System.Management.ManagementObject("Win32_LogicalDisk.DeviceID=" & DriveLetter & ":")

Sample:

Private Function GetVolumeSerial(ByVal DriveLetter As String) As String

    'Check for valid drive letter argument.
    Dim ValidDriveLetters As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    If ValidDriveLetters.IndexOf(DriveLetter) <> -1 Then
    If DriveLetter.Length = 1 Then
        Dim Disk As New System.Management.ManagementObject("Win32_LogicalDisk.DeviceID=""" & DriveLetter & ":""")
        Dim DiskProperty As System.Management.PropertyData
        For Each DiskProperty In Disk.Properties
        If DiskProperty.Name = "VolumeSerialNumber" Then
            Return DiskProperty.Value.ToString  '.ToString 'Return the volume serial number.
        End If
        Next DiskProperty
    End If
    End If
    Return Nothing 'Invalid drive letter.

End Function

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