Imports System.IO
 
Sub Kopieren_starten()
 
        Dim source As String = TextBox1.Text.Trim
        Dim target As String = TextBox2.Text.Trim
 
        Dim fsi As New FileStream(source, FileMode.Open, FileAccess.Read, _
          FileShare.Read)
        Dim fso As New FileStream(target, FileMode.OpenOrCreate, _
        FileAccess.Write, FileShare.None)
 
        Dim bufferSize As Integer = 256
        Dim buffer(bufferSize) As Byte
 
        ProgressBar1.Value = 0
        ProgressBar1.Minimum = 0
        ProgressBar1.Maximum = Math.Ceiling(fsi.Length / bufferSize)
 
        While fsi.Position < fsi.Length
            Dim bytesRead As Integer = fsi.Read(buffer, 0, bufferSize)
            fso.Write(buffer, 0, bytesRead)
            ProgressBar1.Value += 1
            Application.DoEvents()
        End While
        fsi.Close()
        fso.Close()
        ProgressBar1.Value = ProgressBar1.Maximum
 
    End Sub