PowerShell for Windows Admins

Aug 7 2011   9:26AM GMT

MSDiskDriver classes

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

The root\wmi namespace contains four MSDiskDriver related classes

gwmi -Namespace root\wmi -Class msdiskdriver* -List | select name



The first class – MSDiskDriver – is a super class that calls the other three. Documentation appears to be almost non-existent (there are references to an older copy of the WMI SDK but that doesn’t seem to be available. The MSDiskDriver_PerformanceData class is referenced from the

MSDiskDriver_Performance class as the Perfdata property. We will ignore the  MSDiskDriver class and start with the disk geometry


function get-msdiskdrivergeometry  {           
param (           
Add-Type @"
public enum MediaType : int {
Unknown = 0,
RemovableDisk = 11,
HardDisk = 12
Get-WmiObject -Namespace root\wmi -Class msdiskdriver_geometry `
-ComputerName $computer | select InstanceName, Active,            
@{N="DiskType"; E={[mediatype]($($_.MediaType))}},           
Cylinders, TracksPerCylinder, SectorsPerTrack, BytesPerSector           

Define an enumeration for the media types – values 1-10 and 13-22 related to floppy or similar devices

use Get-WmiObject to get the object and display – use the enum to decode the media type

On my machine this produces

InstanceName      : IDE\DiskST9250320AS_____________________________HP07____\5&b0fd174&0&1.0.0_0
Active            : True
DiskType          : HardDisk
Cylinders         : 30401
TracksPerCylinder : 255
SectorsPerTrack   : 63
BytesPerSector    : 512


compare with the results of Win32_DiskDrive

Get-WmiObject Win32_DiskDrive | select PNPDeviceID, Status, MediaType, TotalCylinders,
TracksPerCylinder, SectorsPerTrack, BytesPerSector

PNPDeviceID       : IDE\DISKST9250320AS_____________________________HP07____\5&B0FD174&0&1.0.0
Status            : OK
MediaType         : Fixed hard disk media
TotalCylinders    : 30401
TracksPerCylinder : 255
SectorsPerTrack   : 63
BytesPerSector    : 512

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