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Virtualization has had a dramatic impact on data center efficiency and hardware utilization, but the next major frontier for system consolidation lies with the weight of the operating system. Virtual machines typically run an enterprise-class operating system such as Windows Server, but the sheer size and complexity of Windows Server limits the number of VMs a server can host. Reducing the overhead of an operating system would allow far more VMs on the same system. Microsoft Nano Server, due sometime in the third quarter of 2016 with the release of Windows Server 2016, is one way organizations can maximize the utilization of their servers.
It's important to understand that Microsoft Nano Server is not a direct replacement for the full Windows Server 2016 operating system (OS), or even Server Core in older versions of Windows Server. Instead, Nano Server is intended to serve specific roles in enterprise computing environments typically related to running enterprise services in virtual machines and the cloud.
One limiting factor to scaling vast numbers of virtual machines (VMs) and minimizing the size and corresponding cost of cloud instances is the overhead imposed by the OS. Windows Server 2016 is a big deployment. It's time-consuming to install and configure, and it takes time to boot up. The compute resources required for a complete Windows Server 2016 installation in every VM or cloud instance can drive up compute costs and limit the resources available for more VMs.
Nano Server helps mitigate the compute resources needed for OSes by dramatically reducing the OS's footprint. Microsoft does this by removing a myriad of familiar components -- most notable is the removal of all direct interfaces including the GUI, command prompt and PowerShell console. There is no local login, 32-bit support has been eliminated, and the Microsoft Installer is gone along with a variety of other components. Ideally, the Nano Server VHD should be more than 90% smaller than a full Windows Server 2016 deployment.
Shrinking the OS improves its performance, stability and security. Nano Server boots very quickly, allowing administrators to restart VMs and workloads in a fraction of the time required for full OS restarts. This also works for container-based virtualization, and running Nano Server in a Hyper-V VM should allow more containers to share the VM's space not consumed by a large underlying OS. In addition, there should be far fewer components to patch or update, resulting in less disruption to running workloads. And fewer components present a far smaller attack surface for hackers.
But even though Nano Server is one of the most exciting new Windows Server 2016 features and promises some noteworthy advantages for enterprise computing, there are two wrinkles to consider. First, the lack of any local login or user interface means that deployment and management will need to be accomplished remotely. Second, Nano Server cannot run any typical application that relies on GUI support or other OS resources absent from Nano Server.
So what's left? Nano Server is generally intended to support services and native cloud-based applications. For example, Nano Server would be an excellent alternative for deployment in Hyper-V VMs or clusters running containers or hosting services like file servers, Web servers, Domain Name System servers or other services that can benefit from rapid scalability. Nano Server is also suited for cloud-based applications based on languages such as Python, Java and C# running in VMs or containers. This might limit the use of Nano Server for more traditional local data center deployments, but highly-virtualized and cloud-enabled organizations seeking rapid, scalable deployments might see Nano Server as an ideal OS in some tasks.
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