July 14, 2015. That's the date. Microsoft will terminate extended support for Windows Server 2003. And it's right around the corner. This means that there will be no more patches for security vulnerabilities or non-security defects from Microsoft. Nor will there be support for third-party applications, as defects in the underlying OS can't be addressed.
Yet there is no one-size-fits-all recommendation for what to do with all of your Windows Server 2003 servers. The migration process could take months depending on how complex existing systems are. And options abound. You could migrate to a newer Windows Server OS, Microsoft Azure, Office 365, another cloud provider, or even another server OS. With so many options it may be difficult to make a choice and take action.
For those of you wondering if you could get away with not upgrading and continuing to run Windows Server 2003 after the end-of-life date, we strongly caution you to upgrade. It is tempting to look the other way for a variety of reasons. Maybe you don't patch your servers to begin with, so you don't care that no further patches will be issued. Maybe you have proprietary 16-bit code that can't easily be migrated to a more modern OS. If you want to run the risk of having your server and applications go down due to a newly discovered and exploited security vulnerability, or of your server being used to attack other, more-valuable assets within your infrastructure, we can't stop you. It's up to you, based on what you know about your set up, to decide if the benefits of upgrading exceed the risks of remaining on a platform that is no longer supported.
I will offer you this warning tweeted by Microsoft Distinguished Engineer Jeffrey Snover:
Not updating from WS2003 is like the guy who jumps off a building on the way down says, "so far, so good." #ThisIsNotGoingToEndWell
After all, your Windows Server 2003 servers will not crash and burn on July 14. You could keep running them if you want to. You might even get away with it for a few weeks, months, or maybe even years, especially if your servers are already locked down and aren't connected to the Internet. Yet we strongly caution against this for security, availability, and reliability reasons.
The Advantages of Newer Server Operating Systems
A lot has happened to Windows Server OS in the past 10+ years. Improvements haven't been purely incremental. The entire world of virtualization wasn't present in Windows Server 2003. This includes Hyper-V, desktop virtualization (including session virtualization), virtual desktop infrastructure (VDI), and application publishing (Remote Desktop Services). Massive changes to Active Directory have been implemented, including granular security policies based on group membership, the ability to undelete objects (this alone could be worth an upgrade), federation with other organizations, the ability to publish services to the Internet, and centralized network management.
While you're researching Windows Server 2008, Windows Server 2012, and Windows Server 2012 R2, pay special attention to features that are applicable to your environment. Microsoft offers a comparison of features that's a good place to start. This is not only helpful for your planning but also for preparing for discussions with senior management about why you need to upgrade and budget justifications. Having concrete reasons for upgrading will make it much easier for your boss to pony up.
Windows Server 2012 R2 not only requires beefier hardware than Windows Server 2008 R2, it also supports beefier hardware. So if you anticipate server loads growing beyond the need for a mere 64 logical processors and 1TB of RAM, then looks toward the newer version. Likewise, support for virtual resources is higher in Windows Server 2012 R2, for example, Server 2008 R2 supports a 2TB virtual disk, while Server 2012 R2 supports a 64TB virtual disk. In addition, Windows Server 2012 R2 supports NIC teaming, which could be particularly important in high-performance environments.
There's another practical consideration: Windows Server 2008 R2 will EOL before Windows Server 2012 does. This means that you'll have to go through this whole process again sooner if you choose Windows Server 2008 R2. This reason alone is enough to choose Server 2012 R2.
Conclusion
Faced with the July deadline, you're going to have to migrate to something. There are a lot of options, ranging from physical to virtual, on-premise to cloud, all from a variety of providers. The most straightforward option might be to migrate to a newer version of Windows: Server 2008 R2 or Server 2012 R2. Understanding the applications and services running on your existing Windows Server 2003 instances and the way they use your infrastructure's resources will provide you with insight into which platform to choose next. There is also the important consideration that since Windows Server 2012 R2 is newer, and it will be officially supported longer, which may make it the right choice.
For more, see the first two parts of this series: The Procrastinator's Guide to Windows Server 2003 Migration and Windows Server 2003 Migration Guide: Choosing a Replacement OS.