SCOM - Created a sample MP to create the performance data based on WMI Query

1. Create a Probe-Based (script) performance collection rule & Set Target as “Windows Computer”

2. Select Management Pack and Set the Rule Name.

3. Set the Schedule

4. Type the Name and extension of the script, such as DiskSizeCollectionScript.vbs, timeout value and copy the below script.

5. Set Timeout to the length of time in seconds, minutes, hours, or days, the script can run before it is terminated.

6. On the Performance Mapper page, map parameters from the script to fields [Parameters are case sensitive]

• Object : Disk_Name

• Counter : Disk_Size

• Instance : $Data/Property[@Name='drive']$

• Value : $Data/Property[@Name='diskSize']$

7. Click Ok and create

Reference Link
http://technet.microsoft.com/en-us/library/bb381406(TechNet.10).aspx

'======================Script ================

Dim oAPI, oBag , oArgs , objShell,disksizeGB

' Set SCOM parameters

Set oAPI = CreateObject("MOM.ScriptAPI")

Set oArgs = WScript.Arguments

Set objShell = Wscript.CreateObject("Wscript.Shell")

strComputer = "."

Set objWMIService = GetObject("winmgmts:" & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")

Set colVolume = objWMIService.ExecQuery("Select * from Win32_Volume")

For each objVolume in colVolume

disksizeGB=round(objVolume.Capacity/1024/1024/1024,0)

Set oBag = oAPI.CreatePropertyBag()

Call oBag.AddValue ("DiskName", objVolume.Caption)

Call oBag.AddValue ("DiskSize", diskSizeGB)

Call oAPI.Return(oBag) 

Next

'======================End======================