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This article is part of our Essential Guide: What's the best Linux OS for your enterprise data center?

Choosing the best server OS: Linux vs. Windows comparisons

When determining the best commodity server OS for a data center, you have various Windows and Linux options. And they're anything but equal.

In the corporate data center, Windows and Linux-based servers work side-by-side. But which is the best server operating...

system for your changing workloads?

Experts Sander van Vugt and Brien Posey compare Linux vs. Windows Server on key points to determine the best server OS and dispel some common myths about both options. Follow their assessments of functionality and hardware compatibility, resource requirements, stability and security, as well as cloud-readiness, cost and support.

Operating system functionality

Sander van Vugt: The most significant characteristics for a server OS include functionality, security and stability, as well as vendor support when things go wrong. Also consider the workload: Do you need a cloud-ready OS, or does the application have specific hardware requirements? Windows isn't going away any time soon, in particular as a corporate authentication and authorization platform. But as applications move more to cloud platforms, Windows servers are moving out and making way for Linux as the server OS of choice.

Windows has a reputation as an all-around operating system, and Linux does not. Data centers traditionally deploy Linux servers to offer single services; Windows Server is used for an all-in-one operating system that's easy to manage.

There is no reason why a data center shouldn't install Linux as a multi-purpose operating system, but historically Linux servers deploy for the tasks that they do well, and they handle these astutely. As Linux operating systems are free (not including vendor-based support costs), why not install as many virtual OS instances as you need to handle individual tasks? Services separated onto their own OS increases data center security over many services running together on a multipurpose server.

About our Linux expert

Sander van Vugt

Sander van Vugt is an independent trainer and consultant based in the Netherlands. He is an expert in Linux high availability, virtualization and performance. He has authored many books on Linux topics, including Beginning the Linux Command LineBeginning Ubuntu LTS Server Administration and Pro Ubuntu Server Administration. Sander also presents a video Linux training series for the RHCSA and RHCE exams, with Pearson IT Certification.

Brien Posey: Windows Server was initially an all-in-one operating system, but Microsoft has stressed the concepts of minimizing of the server footprint and using dedicated server roles for many years now. Licensing costs made these dedicated server roles somewhat problematic, until recently.

Today, a Windows Server 2012 or 2012 R2 Datacenter Edition server with Hyper-V virtualization is licensed to run an unlimited number of Windows Server virtual machines. As such, licensing is no longer a consideration for organizations that deploy a large number of virtualized Windows servers.

OS stability

Van Vugt: Linux has a reputation for stability that Windows Server does not, but this is an outdated point. Recent Windows Server operating system versions, from 2003 on, are stable and increasingly so.

Both Windows and Linux OSes can only be brought down by hardware with faulty drivers. Don't choose a server OS based on outdated notions of stability: Windows and Linux are at the same level here.

Posey: Windows Server became a stable operating system over at least the last ten years thanks to rigorous hardware testing and a logo certification program for compatibility guarantees with various hardware devices.

About our Windows expert

Brien Posey

Brien Posey is an eight-time Microsoft MVP for his work with Windows Server, IIS, Exchange Server and file system storage technologies. Brien has served as CIO for a nationwide chain of hospitals and healthcare facilities and was once responsible for IT operations at Fort Knox. He has also served as a network administrator for some of the nation's largest insurance companies.

Cloud readiness

Van Vugt: Started as an initiative of NASA and managed cloud provider Rackspace, OpenStack is a cloud framework run on Linux. Hundreds of leading companies in the computer industry support OpenStack, including Red Hat, and look for it to become the de facto cloud infrastructure in the future. A lot of vendors have a proprietary cloud offering, such as Windows Azure on the Windows Server OS.

Posey: Microsoft markets Windows Server as a cloud operating system, with Microsoft Azure running on top of Windows Server and Hyper-V. Microsoft's software-as-a-service offering of Office 365 also runs on Windows Server and Hyper-V. Both have millions of subscribers.

Many third-party cloud service providers allow customers to create virtualized Windows Server instances in the cloud.

Cost of ownership in the data center

Van Vugt: It's true, Linux is a free operating system. But running Linux in the data center will cost you. The free distributions of Linux don't meet enterprise needs because they offer no guarantees. So let's dispel the myth that Linux is free and Windows is not.

Most companies want the best possible reliability on servers for a good price. Linux itself is free; you'll pay for support. That is why the best Linux server OSes come from vendors such as Red Hat and SUSE that charge for support contracts.

Linux is less expensive than Windows Server because of the pricing structure. There's no such thing as per-user licensing of Linux distributions, for example, so the potential cost saving of migrating servers from Windows to Linux is significant.

Posey: Windows has long had a reputation as an expensive operating system, thanks to the price of the server OS combined with the required Client Access Licenses. Although Windows will likely always be more expensive to license than Linux, Microsoft is making changes to the licensing requirements for some products to appeal to organizations in which users deploy multiple devices.

Security for corporate IT

Van Vugt: Anyone can look at how an open source operating system like Linux is organized. Some people consider this a disadvantage for security. However, the fact that various interested parties freely access different aspects of the operating system makes it easy to detect and fix bugs. In a proprietary operating system like Windows Server, the company using the software can observe a bug but cannot fix it.

While open source doesn't hide the operating system's inner workings, security is a part of the Linux kernel, and sophisticated mandatory access control systems like Security-Enhanced Linux, invented in collaboration with the U.S. National Security Administration and Red Hat, are built on top of that. Security administrators can block all unneeded system calls, for example. There is nothing comparable to SELinux for Windows Server.

Posey: Microsoft routinely releases security patches for the Windows Server operating system as new vulnerabilities are discovered. Microsoft also provides extensive documentation on how to use built-in Windows Server security controls, as well as tips for establishing a network architecture that achieves the best possible security.

Data center hardware needs

Van Vugt: We can be brief about Linux OS hardware needs, which are smaller than Windows. You can run a decent server on as little as 256 MB of RAM and a disk with just a couple of gigabytes capacity, but that's not the typical workload in a corporate data center.

For huge database systems, the operating system overhead of Linux is smaller versus Windows Server. And the Linux kernel is highly tunable, allowing administrators to make it even more efficient.

Posey: The hardware requirements for Windows Server 2012 R2 vary depending on the server's workload, but Windows Server can run on a system that has as little as 512 MB of RAM and a 1.4 GHz (64-bit) CPU.

Vendor support for the server OS

Van Vugt: Companies don't operate servers because they want to run a server. Companies rely on servers because they want the applications that support the business. It's a common belief that Windows offers bigger vendor support than Linux systems, but that is changing rapidly. As more applications move from the server to the cloud, corporations are mainly keeping big applications in house: Oracle and SAP, among others. Both Windows and Linux OSes support these apps.

Posey: Microsoft is universally supported by the major server hardware vendors. Although some of the vendors might also offer servers that are provisioned with competing operating systems, they all support Windows Server.

It isn't enough for the server manufacturers to support a particular operating system. For that OS to really be useful, IT shops need drivers readily available for add-on hardware. Nearly all of the hardware manufacturers provide Windows drivers for their products.

Corporate authentication

Van Vugt: One area where Windows servers are still huge is corporate authentication. Active Directory is a full authentication and authorization platform that integrated applications, users, computers and other resources. Linux alternatives to Active Directory don't have the same support of devices and applications.

Posey: Microsoft Active Directory is the de facto standard for authentication because it is solid, reliable and secure, and in addition is widely supported by an array of third-party products.

Next Steps

While Linux is a threat in the data center, Windows continues long-time domination on the desktop. And the two OSes aren't mortal enemies -- sometimes Hyper-V can give a boost to Linux VMs.

After Windows Server Core failed to catch on, Microsoft may convince administrators with Nano Server for a more VM- and cloud-friendly Windows Server deployment.

Ubuntu Core can add extra security to your Linux distribution.

This was last published in December 2014

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How many different server OSes are running in your data center today?
We use Unix for email delivery, Linux for free software and web servers, and windows for directory services. Using Sendmail and Procmail for SMTP and email delivery is way easier than using Exchange. Creating web servers on the fly is simple with Linux and database servers are so easy to maintain and update too. The distro of Linux for us is Debian for the ease of upgrading and patching.
Hey Robert, Do you find managing several OSes to be time consuming or is it negligible? Or is it a case where investing in a little extra training/interface skills = big payoff in the functionality you get for the cost of different OSes?
Using multiple server OS's is not as time consuming as you might think. All Linux and Unix OS's can be updated or patched with scripts for minor updates, major updates are done by hand during scheduled down times. Microsoft provides WSUS for the Windows operating systems. The issue come in when you have multiple distributions of Linux and knowing how each distribution is updated. Using test servers helps with testing of major updates.
It would be worth mentioning that even if Active Directory is in use for corporate authentication, it is straightforward to integrate Linux servers into Active Directory. We do it all the time on very large systems, using integration products from Centrify, Likewise, or even just native Samba libraries in some cases, depending on the use case.
There is only one choice for freedom of use, at any scale.
And what's that choice, zman5819?
The choice of numerous DB engines, mail applications, web servers, DNS applications, clustering, and the list is on and on. Let's face it, from an application perspective, MS gives you their solution. If you like it great. If you want to the options, linux beats MS any day.
Microsoft may be more widely used and have limited application options and higher costs. If they suit your needs, great. As for tighter security and the number of options available on the open source market, and budget friendly, I can see Linux gaining more respect. Then it comes down to what your staff can work with.
This whole comparison is hogwash without comparing the workings of the respective file systems.

Windows never checks if your data is really still there, uncorrupted, with no blocks missing, until you try to access it.