Deprecation of the OSVersion Property and What to Do About It

The OSVersion variable is populated with a short string representing the version of the operating system (e.g. XP, Vista, Win7Client, 2008, etc.).  With MDT 2012, you may have noticed that when you deploy Window 8 that the value of the OSVersion variable gets set to “Other” instead of something like “Win8”.  This is because the MDT team has deprecated the OSVersion property.  The logic that set this property has not been updated for Windows 8 and will no longer be updated.  The team decided that using these string values in script logic leads to hidden bugs and unexpected behavior as new OS versions are released.  For example, code testing for a client OS that is Windows Vista or higher would require something like this using OSVersion:

If oEnvironment.Item("OSVersion") = "Vista" Or oEnvironment.Item("OSVersion") = "Win7Client" Then…

This would work until Windows 8 was released.  Then this would have to be updated with another OR with the Windows 8 value.  They now recommend using a variables like OSCurrentBuild or OSCurrentVersion (e.g. the values for Windows 7 SP1 would be 7601 and 6.1.7601 respectively).  So the equivalent code using OSCurrentBuild would look like this and would continue to work as new operating systems are released:

If CInt(oEnvironment.Item("OSCurrentBuild")) >= 6000 And UCase(oEnvironment.Item("IsServerOS") = "FALSE" Then...

While I wholeheartedly agree with this reasoning, there is one instance where I like an easily recognized string for the OS version.  This is composite custom property called ModelOSArchAlias that I defined in my Model Alias post. which combines the ModelAlias, OSVersion, and Architecture properties.  These values are used to create Make and Model entries in the MDT database.  Using OSCurrentBuild instead of OSVersion would lead to ModelOSArchAlias values like ThinkPadT420_7601_X64 instead of the more easily readable ThinkPadT420_Win7Client_X64.  I see it becoming easy to confuse which version you are referencing with an OSCurrentBuild of 6002, 7601, 9200, or 9600 (Windows Vista SP2, Windows 7 SP1, Windows 8, and Windows 8.1 respectively).

So to make it possible to use a short string representing the version of the operating system that is current, I’ve created a function called GetOSVersionTag that is essentially a copy of the ZTIGather.wsf code that sets OSVersion with some improvements and updated to set proper values for Windows 8, Windows Server 2012, Windows 8.1, and Windows Server 2012 R2.  I have placed this function in a class library script that I have been building up over the years called MDTLibHelperClasses.vbs.  This script is conceptually similar to ZTIUtility.vbs.  It can be referenced similarly in other MDT scripts and using the technique from my last post it can also be used as a User Exit script.  As I create new general purpose functions going forward, I will place them in future versions of this library as appropriate.

To use this function to create a custom variable called OSVersionTag and use that in ModelOSArchAlias, add MDTLibHelperClasses.vbs (and MDTExitInclude.vbs and ModelAliasExit.vbs from the two previous posts referenced earlier) to the Scripts folder of your Deployment Share or Configuration Manager MDT Files package and add the following to CustomSetting.ini (used during Gather in the newly deployed OS):

Priority=IncludeExitScripts, ModelAliasVars, Default
Properties=ExitScripts(*), OSVersionTag, ModelAlias, ModelOSArchAlias





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This post was contributed by Michael Murgolo, a Senior Consultant with Microsoft Services - U.S. East Region