How to get notified when a drive letter becomes available

Question

Is it possible to get notified (without polling, but via an event) when a drive letter becomes accessible. For example if you have an external hard drive that always appears as drive F - is it possible to have an event raised when that is connected and F becomes accessible?

Answer 1

Okay.. found what I was looking for :)

Take a look at this VBScript: (source):

strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")

Set colEvents = objWMIService.ExecNotificationQuery _
    ("Select * From __InstanceOperationEvent Within 10 Where " _
        & "TargetInstance isa 'Win32_LogicalDisk'")

Do While True
    Set objEvent = colEvents.NextEvent
    If objEvent.TargetInstance.DriveType = 2 Then 
        Select Case objEvent.Path_.Class
            Case "__InstanceCreationEvent"
                Wscript.Echo "Drive " & objEvent.TargetInstance.DeviceId & _
                    " has been added."
            Case "__InstanceDeletionEvent"
                Wscript.Echo "Drive " & objEvent.TargetInstance.DeviceId & _
                    " has been removed."
        End Select
    End If
Loop

I leave it to your exercise to port it to C#.

Instead of polling all the time you can use a WMI event sink.

Answer 2

You can wait for the WM_DEVICECHANGE message, all the details are at:

http://msdn.microsoft.com/en-us/library/aa363215(VS.85).aspx

You're going to have to create a window to receive this message, the window can be hidden if you need, to get this message in WinForms just override the Form.WndProc method