• Illustration: Windows Server Roadmap

The last 32-bit release of Windows Server will be Windows Server 2008, formerly code-named Longhorn and due in late 2007. Successor editions of the Windows Server OS and derivatives such as Windows Compute Cluster and Storage Server will be 64-bit only. The move reflects the fact that most computers are now sold with a 64-bit processor, though the lack of 64-bit device drivers means most still run a 32-bit edition of Windows. However, Microsoft has not clarified the future of 32-bit processor support for the Windows client or of the Itanium 64-bit architecture on the server.

(For an overview of the roadmap for Windows Server and several derivative products, see the illustration "Windows Server Roadmap".)

Beginning of the End for 32-Bits

Bill Laing, the general manager of the Windows Server division, used his keynote address at the May 2007 Windows Hardware Engineering Conference (WinHEC) to announce the 64-bit-only Windows Server roadmap. Previously, Microsoft had announced that future versions of most server products, such as SQL Server and Exchange, would be available only for 64-bit processors. Now Windows Server appears set to become 64-bit only.

Microsoft will continue to support the current 32-bit Windows editions through each existing product's normal life cycle of Mainstream and Extended support. Therefore, it will be at least 10 years before Microsoft can officially retire the 32-bit Windows Server code base.

Client Future Uncertain

Although some customers interpreted Laing's remarks as applying to both client and server versions of Windows, Laing was in fact only speaking for the server division. On the client, adoption of 64-bit Windows editions will continue to be gated by the availability of 64-bit device drivers.

A key strength of Windows is the large and diverse set of supported devices. For example, in his WinHEC keynote, Mike Nash, corporate vice-president of Windows product management, said that Vista ships with 20,000 device drivers in the box, with an additional 13,000 drivers available through Windows Update. Nash also indicated that Vista supports 1.9 million devices.

However, many of these device drivers do not work with 64-bit Windows. Servers generally use a narrow range of hardware, and customers typically do not combine new servers with older peripherals. Consequently, on servers the supply of 64-bit Windows drivers is catching up with demand. Desktops and laptops, on the other hand, support a much larger array of device types, and consumers frequently use older peripherals (such as printers) with new computers. As a result, the lack of 64-bit drivers is much more limiting on the client.

Microsoft has strong incentives to make the client OS that follows Windows Vista 64-bit only. The Windows client and server teams regularly swap core Windows files, such as the kernel and networking components, making it expensive and difficult for Microsoft to maintain a 32-bit client OS without a corresponding server. By announcing the impending end of 32-bit versions of Windows Server several years early, Microsoft could spur development of signed 64-bit drivers, making it feasible to move the client OS to 64 bits as well.

Given that the next client OS version may not appear until 2009 or later and, like Vista, may not run well on most hardware purchased before 2006, Microsoft may later conclude that it has little to lose by creating only a 64-bit version of that OS. By then, most hardware will probably ship with 64-bit drivers.

Itanium and Embedded Support Unchanged

Windows Server today supports two 64-bit architectures, Itanium and the x64 architecture used in both AMD and Intel processors. The x64 architecture now dominates, and in Dec. 2005, Microsoft announced that most of its server products would be available only in x64-bit editions. However, Microsoft has continued to support Itanium on the Windows Server OS and SQL Server. It remains unclear how long this support will be continued.

Laing announced that future derivative products of Windows Server, such as Windows Computer Cluster and Storage Server, will not run on the Intel Itanium 64-bit architecture. However, he did not clarify the future of Itanium on the Windows Server OS itself.

New Small Business Server

Laing's updated roadmap also contains information on several Windows Server 2008 derivatives, which will be based on Windows Server 2008. In particular, 2008 will see Microsoft release two new servers to target small and medium-size businesses.

"Cougar" (a code name) is the next version of Microsoft Small Business Server. It will be based on Windows Server 2008 and could include Exchange Server 2007, Windows SharePoint Services 3.0, SQL Server 2005, and the System Center Essentials computer configuration and monitoring product. It is not clear how Microsoft will handle upgrade issues for current Small Business Server customers using a 32-bit version.

"Centro" (a code name) is a previously announced integrated product targeting midsize organizations and will likely be based on Windows Server 2008. Centro will also probably include Exchange 2007, Windows SharePoint Services 3.0, and System Center Essentials. To differentiate it from Cougar, Centro could also include Forefront Client Security. The actual components of both Centro and Cougar are subject to change.

Resources

Bill Laing's WinHEC keynote address can be viewed at www.microsoft.com/winhec/VirtualWinHECKeynotes.mspx.

A description of the driver support in x64-based versions of Windows is available at support.microsoft.com/kb/896333.

A brief description of Cougar is available at www.microsoft.com/windowsserver2003/sbs/evaluation/faq/roadmap.mspx.

A similar description of Centro is available at www.microsoft.com/presspass/features/2005/sep05/09-06Infrastructure.mspx.