Question

I am trying to print (to a text file) the fragmentation information give by Win32_Volume class using the DefragAnalysis method and have come up with the following VB.NET code:

Dim objReader As StreamWriter
        objReader = New StreamWriter(FolderBrowserDialog.SelectedPath + "\FragInfo" + "_" + CreationDate + ".txt")

        Dim colItemsFragInfo As New ManagementObjectSearcher("root\CIMV2", "Select * from Win32_Volume where DriveType = 3")

        For Each queryObj As ManagementObject In colItemsFragInfo.Get()
            objReader.WriteLine("Analyzing volume " + queryObj("DriveLetter"))

            Dim InParams As ManagementBaseObject = queryObj.GetMethodParameters("DefragAnalysis")
            Dim OutParams As ManagementBaseObject = queryObj.InvokeMethod("DefragAnalysis", InParams, Nothing)

            MsgBox(OutParams("VolumeSize"))
            objReader.WriteLine(" Volume size: " + OutParams("VolumeSize"))
        Next

        objReader.Close()

    Catch err As ManagementException
        MessageBox.Show("An error occurred while trying to execute the WMI method: " & err.Message)
    End Try

The thing i cannot get my head around is how to get the parameter info (i.e. “VolumeSize”) from the method “DefragAnalysis”. The above code returns an “Method not found error”.

Thank you

-Edit
This is what currently works when executed in WMI Code Creator:

Imports System
Imports System.Management
Imports System.Windows.Forms

Namespace WMISample

    Public Class MyWMIQuery

        Public Overloads Shared Function Main() As Integer

            Try

            Dim colItemsVolInfo As New ManagementObjectSearcher("root\CIMV2", "Select * from Win32_Volume where DriveType = '3'")

            For Each queryObj As ManagementObject In colItemsVolInfo.Get()

                Dim OutParams As ManagementBaseObject = queryObj.InvokeMethod("DefragAnalysis", Nothing, Nothing)
                Console.WriteLine(" Volume size: {0}MB", Math.Round(OutParams("DefragAnalysis")("VolumeSize")) * (9.53674316 * 10 ^ -7))
                Console.WriteLine(" Cluster size: {0}MB", Math.Round(OutParams("DefragAnalysis")("ClusterSize")) * (9.53674316 * 10 ^ -7))

                If OutParams("DefragRecommended") = True Then
                    Console.WriteLine("You should defragment this volume.")
                Else
                    Console.WriteLine("You do not need to defragment this volume.")
                End If
                    Next

        Catch err As ManagementException
            MessageBox.Show("An error occurred while trying to execute the WMI method: " & err.Message)

        End Try
        End Function
    End Class
End Namespace

WMI Output:
Volume size: 40857.9960763451MB
Cluster size: 0.003906249998336MB
You do not need to defragment this volume.

However executing this in Visual Studio returns the below:
Volume size: MB
Cluster size: MB
You do not need to defragment this volume.

The point here is though it does NOT work under Windows Server 2008 R2, but does work under Windows Server 2003 (when executed in Visual Studio), WMI Code will work regardless of platform.

NB: i have played with the “Console.WriteLine” and changed it to “Debug.WriteLine” to output value to immediate window.

Answer 1

There is no property as VolumeSize.

When you call DefragAnalysis() it returns the status of the function and outs parameters boolean DefragRecommended and object DefragAnalysis.

DefragAnalysis Class contains property VolumeSize.

Console.WriteLine("DefragRecommended: {0}", outParams("DefragRecommended"))
Console.WriteLine("VolumeSize: {0}", outParams("DefragAnalysis")("VolumeSize"))
Console.WriteLine("ReturnValue: {0}", outParams("ReturnValue"))

You should always read the documentation instead of making a guess.

I would like to suggest a nice tool called WMI Code Creator v1.0. This tool tool allows you to generate VBScript, C#, and VB .NET code that uses WMI to complete a management task such as querying for management data, executing a method from a WMI class, or receiving event notifications using WMI.

I hope this helps. : )