Key Value Pair Exchange WMI Component Property GuestIntrinsicExchangeItems & Assumptions

Now that Windows 2008 R2 SP1 is being deployed some scripts to check whether the Integration Components (IC) in Hyper-V VM guests are upgraded came back on the radar screen. Host are being upgraded and thus the clients need upgraded IC as well. Now to check this for hundreds or thousands of guest we need some automation. PowerShell comes in handy for this and some neat scripts can be found around the internet. The most concise PowerShell code to do this, that I know of, is the one Peter Noorderijk (great Dutch IT Pro)  uses in his  PowerShell function Get-IntegrationServicesVersion on his blog How to check the version of the Integration Components.  As he provided this script just when I needed one I used it. This worked fine until I ran into an issue with it on some clusters. On two test cluster and two production clusters it did the job as expected. On one test cluster and one production cluster we ran into the situation where the output seemed wrong. The screenshot below is an example of this.

image

The red arrows indicate wrong data for the VMname and ICVersion. What happened here?  Well when we read out the  GuestIntrinsicExchangeItems property from the WMI object Msvm_KvpExchangeComponent we get back XML. That XML needs to be parsed to display it for human consumption. The  function depends on fixed positions containing the correct data. I’ve marked the relevant portions with a red arrow above, they come from$vmkvp[0] en $vmkvp[14] in the script below.

function Get-Integ.rationServicesVersion ($HVhost = $(throw “HVHost required”))
    {
    $kvps = Get-WmiObject -Namespace rootvirtualization -ComputerName $HVHost -Query “Select GuestIntrinsicExchangeItems From Msvm_KvpExchangeComponent”
        foreach ($kvp in $kvps)
         {
         $vmkvp = $Kvp.GuestIntrinsicExchangeItems
         $vmkvp | select-object @{Label=”VMHost”;Expression={$hvhost}},
                                @{Label=”VMName”;Expression={($vmkvp[0]).instance.property[1].value}},        
                                @{Label=”ICVersion”;Expression={($vmkvp[14]).instance.property[1].value}} -first 1
         }    
    }
  
foreach ($hvhost in get-content servers.txt) {Get-IntegrationServicesVersion $hvhost}

And indeed, when we dump the XML for two of the affected servers out to text files you can see the order is indeed different so counting on the exact location in an array is what tripped us up here.

image

Should this ever happen? Am I making a scripting mistake somewhere? Running a check with a VBScript that parses the XML  using XDOM (just in case my PowerShell skills are the cause of this) confirms the order is different but that the key pairs match up and are correct

D:SysAdminPowerShellScripts>cscript.exe test.vbs

Microsoft (R) Windows Script Host Version 5.8

Copyright (C) Microsoft Corporation. All rights reserved.

Guest OS information for server01

CSDVersion : Service Pack 1

FullyQualifiedDomainName : server01.lab.test

IntegrationServicesVersion : 6.1.7601.17514

NetworkAddressIPv4 : 10.10.100.118

NetworkAddressIPv6 : fe80::a177:729:8840:250%9

OSBuildNumber : 7601

OSEditionId : 7

OSMajorVersion : 6

OSMinorVersion : 1

OSName : Windows Server 2008 R2 Standard

OSPlatformId : 2

OSVersion : 6.1.7601

ProcessorArchitecture : 9

ProductType : 3

RDPAddressIPv4 : 10.10.100.118

RDPAddressIPv6 : fe80::a177:729:8840:250%9

ServicePackMajor : 1

ServicePackMinor : 0

SuiteMask : 272

D:SysAdminPowerShellScripts>cscript.exe test.vbs

Microsoft (R) Windows Script Host Version 5.8

Copyright (C) Microsoft Corporation. All rights reserved.

Guest OS information for server13

FullyQualifiedDomainName : server13.lab.test

OSName : Windows Server 2008 R2 Standard

OSVersion : 6.1.7601

CSDVersion : Service Pack 1

OSMajorVersion : 6

OSMinorVersion : 1

OSBuildNumber : 7601

OSPlatformId : 2

ServicePackMajor : 1

ServicePackMinor : 0

SuiteMask : 272

ProductType : 3

OSEditionId : 7

ProcessorArchitecture : 9

IntegrationServicesVersion : 6.1.7601.17514

NetworkAddressIPv4 : 10.10.100.112

NetworkAddressIPv6 : fe80::c18b:e3f2:7f05:31e4%12

RDPAddressIPv4 : 10.10.100.112

RDPAddressIPv6 : fe80::c18b:e3f2:7f05:31e4%12

When I look at where that data lives in the registry on those servers it all looks exactly the same, neatly ordered buy the regedit GUI:

image
image

So when getting that data from the Key Value Pair Exchange WMI component with the property GuestIntrinsicExchangeItems you get a bunch of XML. That has to be parsed to be displayed in a readable fashion. The problem we are seeing is due to the fact that the items in the XML file are not in the same order. Peter’s function assumes it is. However this does not happen to be the case for most virtual machines, the majority is in the expected order. I don’t know why that is or if this is supposed to happen but it doesn’t seem to cause any harm. All is fully functional and operational in Hyper-V Manager, SCVMM 2008R2 … etc. Perhaps an MVP or Microsoft guru can shed some light on this. It seems like a bug waiting to happen if a developer of Hyper-V management software makes the same assumption. Of is this never suppose to happen and do I need to worry? I don’t know Smile I reinstalled the IC on the guests that have a different ordering and live migrated them, but that didn’t change anything

Anyway if you want to make sure you get the correct output we’ll need another approach that doesn’t make assumptions.You can roll your own and get the output customized to your needs but you need to parse the XML using a filter.  An example of which is listed below.

# Filter for parsing XML data
filter Import-CimXml 
{    
# Create new XML object from input  
$CimXml = [Xml]$_    
$CimObj = New-Object -TypeName System.Object     

# Iterate over the data and pull out just the value name and data for each entry   
foreach ($CimProperty in $CimXml.SelectNodes("/INSTANCE/PROPERTY[@NAME='Name']"))      
 {          
     $CimObj | Add-Member -MemberType NoteProperty -Name $CimProperty.NAME -Value $CimProperty.VALUE       
 }  
    
 foreach ($CimProperty in $CimXml.SelectNodes("/INSTANCE/PROPERTY[@NAME='Data']"))     
   
 {         
     $CimObj | Add-Member -MemberType NoteProperty -Name $CimProperty.NAME -Value $CimProperty.VALUE      
 }    


# you send the output from the property to the filter via a pipe
$KvpComponentVMGuest.GuestIntrinsicExchangeItems $vmkvp |Import-CimXml 

Maarten Wijsman (a fellow blogger at http://www.hyper-v.nu like Peter)  has a nice example script here that also uses a filter Import-CimXML. Do note that there are  variants on this filter depending on what output you desire that explains the difference between the filters.

1 thought on “Key Value Pair Exchange WMI Component Property GuestIntrinsicExchangeItems & Assumptions

  1. Pingback: Integration Services Version Check Via Hyper-V Integration/Admin Event Log | Working Hard In IT

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