Managing Operating System and Framework Versions
When you publish your cloud service in Windows Azure, it provisions a virtual machine for each role instance in the cloud service. The osFamily setting for each role in a cloud service project determines the version of the operating system that's installed on each virtual machine. Visual Studio sets the osFamily setting automatically when you create a project. The setting is determined by the .NET Framework version that you specify when you create a cloud service project, and the setting may also depend on the version of the Windows Azure Tools that you're using. You can change the osFamily setting in this file if you want Windows Azure to provision a different operating system for your role’s instances. For example, you might want to change this setting if you change the version of the .NET Framework that your project targets or if your application depends on some other version-specific features of the operating system. The osFamily setting is saved in the .cscfg file as an attribute of the ServiceConfiguration element. The .cscfg file is a plain text file that contains XML elements.
This section shows you what Windows operating system is installed for each value of the osFamily code in the .cscfg file. The table also shows the .NET Framework versions that are included with that operating system as provisioned by Windows Azure.
.NET Framework version or versions
Windows Server 2008
Windows Server 2008 R2
Windows Server 2012
If you change your osFamily setting by editing the .cscfg file, make sure that the corresponding version of the operating system includes the version of the .NET Framework that your project requires. To determine what version of the .NET Framework your cloud service targets, open the shortcut menu for the project node for a role, and then choose Properties. On the Application tab, choose the .NET Framework version in the Target Framework list.