Powershell (v2) - Get-WmiObject: Get Class Definitions

My past exploits have led me to become much more familiar with WMI than I had ever hoped to be.  As a result, I know how to get around the information provided by WMI pretty well.  Yet, this morning, I needed to figure out how large a given field for the Win32_LogicalDisk Description property could be and wasn't quite sure how to do it with Powershell.  I tried a few approaches (listed below), but, none of them worked.  You can walk through each to see what it returned as an exercise:

• Get-WmiObject -Class Win32_LogicalDisk | select *
• Get-WmiObject -Class Win32_LogicalDisk | Get-Member
• Get-WmiObject -Class Win32_LogicalDisk | Get-Member | select *
• Get-WmiObject -Class Win32_LogicalDisk | Get-Member | select * | ft -auto
• Get-WmiObject -Class Win32_LogicalDisk | Get-Member | select * | Format-Wide
• Get-WmiObject -list win32_logicaldisk
• Get-WmiObject -class Win32_LogicalDisk | Get-Member -name Description
• Get-WmiObject -class Win32_LogicalDisk | Get-Member -name Description | select *

At this point I decided to go a different route and look at the class definition itself. This link,

http://www.codeproject.com/KB/system/WQLByExample.aspx

helped me get the right query to figure out how to do that.  The meta_class object had escaped memory.  Once I had the appropriate reference

Get-WmiObject -Query "select * from meta_class where __Class = 'Win32_LogicalDisk'"

As noted in the article,

Schema queries are used to get information about WMI itself and its structure.

To illustrate how to use this, the author gives and example,

Select * From Meta_Class

and explains,

This is the most basic schema query. You can connect to any WMI namespace and use this query to get all the classes present in it. Meta_Class is a meta class used only in schema queries.

There are several other directions I could go with this, but, I don't want to get too far off into WMI details. When you run the query listed above to gather __Class details for Win32_LogicalDisk it returns specific properties and class definitions for each property. Here is my walkthrough to get the specific properties and their definitions:

PS > Get-WmiObject -Query "select * from meta_class where __Class = 'Win32_LogicalDisk'"


NameSpace: ROOT\cimv2

Name Methods Properties
---- ------- ----------
Win32_LogicalDisk {SetPowerState, R... {Access, Availability, BlockSize, Caption...}


PS > $Win32_LogicalDisk = Get-WmiObject -Query "select * from meta_class where __Class = 'Win32_LogicalDisk'"

PS > $Win32_LogicalDisk.__CLASS
Win32_LogicalDisk

PS > $Win32_LogicalDisk | % {$_}


NameSpace: ROOT\cimv2

Name Methods Properties
---- ------- ----------
Win32_LogicalDisk {SetPowerState, R... {Access, Availability, BlockSize, Caption...}


PS > $Win32_LogicalDisk | % {$_.Properties}


Name : Access
Value :
Type : UInt16
IsLocal : False
IsArray : False
Origin : CIM_StorageExtent
Qualifiers : {CIMTYPE, read}

Name : Availability
Value :
Type : UInt16
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, MappingStrings, read, ValueMap}

Name : BlockSize
Value :
Type : UInt64
IsLocal : False
IsArray : False
Origin : CIM_StorageExtent
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : Caption
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_ManagedSystemElement
Qualifiers : {CIMTYPE, MaxLen, read}

Name : Compressed
Value :
Type : Boolean
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : ConfigManagerErrorCode
Value :
Type : UInt32
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read, ValueMap}

Name : ConfigManagerUserConfig
Value :
Type : Boolean
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read}

Name : CreationClassName
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIM_Key, CIMTYPE, read}

Name : Description
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_ManagedSystemElement
Qualifiers : {CIMTYPE, read}

Name : DeviceID
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIM_Key, CIMTYPE, key, MappingStrings...}

Name : DriveType
Value :
Type : UInt32
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : ErrorCleared
Value :
Type : Boolean
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read}

Name : ErrorDescription
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read}

Name : ErrorMethodology
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_StorageExtent
Qualifiers : {CIMTYPE, read}

Name : FileSystem
Value :
Type : String
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : FreeSpace
Value :
Type : UInt64
IsLocal : False
IsArray : False
Origin : CIM_LogicalDisk
Qualifiers : {CIMTYPE, read}

Name : InstallDate
Value :
Type : DateTime
IsLocal : False
IsArray : False
Origin : CIM_ManagedSystemElement
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : LastErrorCode
Value :
Type : UInt32
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read}

Name : MaximumComponentLength
Value :
Type : UInt32
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : MediaType
Value :
Type : UInt32
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : Name
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_ManagedSystemElement
Qualifiers : {CIMTYPE, read}

Name : NumberOfBlocks
Value :
Type : UInt64
IsLocal : False
IsArray : False
Origin : CIM_StorageExtent
Qualifiers : {CIMTYPE, MappingStrings}

Name : PNPDeviceID
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read}

Name : PowerManagementCapabilities
Value :
Type : UInt16
IsLocal : False
IsArray : True
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read}

Name : PowerManagementSupported
Value :
Type : Boolean
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, read}

Name : ProviderName
Value :
Type : String
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : Purpose
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_StorageExtent
Qualifiers : {CIMTYPE, read}

Name : QuotasDisabled
Value :
Type : Boolean
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, read}

Name : QuotasIncomplete
Value :
Type : Boolean
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, read}

Name : QuotasRebuilding
Value :
Type : Boolean
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, read}

Name : Size
Value :
Type : UInt64
IsLocal : False
IsArray : False
Origin : CIM_LogicalDisk
Qualifiers : {CIMTYPE, read}

Name : Status
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_ManagedSystemElement
Qualifiers : {CIMTYPE, MaxLen, read, ValueMap}

Name : StatusInfo
Value :
Type : UInt16
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIMTYPE, MappingStrings, read, ValueMap}

Name : SupportsDiskQuotas
Value :
Type : Boolean
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, read}

Name : SupportsFileBasedCompression
Value :
Type : Boolean
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : SystemCreationClassName
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIM_Key, CIMTYPE, Propagated, read}

Name : SystemName
Value :
Type : String
IsLocal : False
IsArray : False
Origin : CIM_LogicalDevice
Qualifiers : {CIM_Key, CIMTYPE, Propagated, read}

Name : VolumeDirty
Value :
Type : Boolean
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}

Name : VolumeName
Value :
Type : String
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read, write}

Name : VolumeSerialNumber
Value :
Type : String
IsLocal : True
IsArray : False
Origin : Win32_LogicalDisk
Qualifiers : {CIMTYPE, MappingStrings, read}