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Microsoft Nano Server: A lighter OS for heavy workloads

Microsoft has streamlined its server operating system to address the problems associated with running a larger-than-necessary server OS in the data center. Call it addition by subtraction.

Microsoft Nano Server is a no-frills 64-bit server operating system debuting in Windows Server 2016. The default deployment has no graphical user interface (GUI) nor any embedded server roles. The administrator builds Nano Server's deployment to handle a specific task. Nano Server can act as a host for containers or Hyper-V VMs. It also functions as a domain name system or web server.

By only adding the services a workload needs, the size of a typical Microsoft Nano Server deployment is about 400 to 600 megabytes (MB). In contrast, using Windows Server 2012 as a Hyper-V host consumes around 12 GB of disk space on top of an application, which may only use 200 MB. The large size of the full server OS also eats up other valuable resources, including CPU cycles, RAM and network bandwidth.

Nano Server will help enterprises avoid the cascading costs associated with heavier VMs -- more network bandwidth, more powerful servers and additional storage, says Thomas Maurer, a Microsoft MVP for Hyper-V and a cloud architect for Swiss-based itnetX.

"If you can make those [server] operating systems smaller and consume less resources, you can deploy more VMs on the same hardware. This would save you some money," Maurer says.

Another benefit attributed to Nano Server's minimal footprint is the smaller code base. Less code means a smaller attack surface. Microsoft estimates it will release 92% fewer critical patches for Nano Server compared to the full Windows Server deployment. Because most security patches require a reboot to take effect, this change should benefit organizations that need to avoid downtime.

Despite these advantages, there is a learning curve associated with using Nano Server and, for some administrators, it will require a "total rethinking" with both deployment and management.

"This is really going to be a big change for a lot of people out there," Maurer says. "For all us Windows administrators who used Windows Server now for years, this is completely different."

To deploy Microsoft Nano Server, the administrator takes the base Nano Server image and uses PowerShell to add packages that infuse more functions. The challenges for IT pros don't end there. Nano Server is a headless deployment, so administrators cannot log in to the server locally. They must use PowerShell or another tool such as Microsoft Windows Server Manager to troubleshoot problems or make modifications.

Goodbye full-scale OSes?

While Microsoft Nano Server will lift the OS burden for certain scenarios and applications, it won't fill every server role.

"Nano Server, in the short term right now, won't replace Windows Server or the full server for everyone," Maurer says. "There are still some features missing and also, for probably smaller environments, you don't have the need for Nano Server, and you [will] probably prefer the full server."

Microsoft already has another minimal server OS, Server Core, which arrived in 2008. Microsoft removed the GUI in Server Core but left many other server technologies intact. By removing certain features, a typical Windows Server 2012 Server Core install takes about 6 GB of drive space. Like Nano Server, Server Core cannot be managed from a desktop interface.

Microsoft will keep the Server Core option in Windows Server 2016 but says the even smaller Nano Server will appeal to companies that need to launch many virtualized instances in rapid fashion. Experts say the development of a key ingredient -- the advanced PowerShell modules needed to deploy and manage Nano Server -- could spur adoption rates for other organizations that may not be comfortable using Nano Server outside of a lab environment.

"With [Windows Server Core] 2008 or 2008 R2, there was PowerShell; but to be honest, there weren't really good PowerShell modules available," Maurer says, noting those versions of Server Core lacked key PowerShell features for Hyper-V clustering and management. But this paradigm changes with Nano Server and now "[w]e have PowerShell that can really do some serious management, and [administrators] can basically do everything using PowerShell."

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