Windows 64-bit: Frequently Asked Questions

Fundamentally, 64-bit products—from servers to software applications—make use of an architecture that provides the ability to double the size of the fundamental unit of data handled by processors while preserving compatibility with the 32-bit x86 architecture that has been in use for decades.

This doubling has a variety of implications. The ability to double gives systems the capacity to make effective use of far more virtual and physical memory while performing certain computations more quickly.

For customers, this can translate to benefits ranging from faster photo editing on desktop systems to cost savings due to the consolidation of several smaller servers to a single, higher-performing system.

Most new Windows Server systems today can run the x64 edition of Windows Server. However, if you have any concerns about a system, consult the manufacturer.

Windows Server products for Itanium-based systems require a system based on the Itanium architecture. For more information, see the list of manufacturers of Itanium-based systems or visit the Itanium Solutions Alliance site.

While each product team has a unique roadmap, Microsoft has broadly committed to its applications supporting the x64 platform. The majority of our client applications, such as the 2007 Office system and Microsoft Visual Studio 2005, are supported in 32-bit mode on x64 Windows. Microsoft's Common Engineering Criteria for Windows Server System require all new releases of Windows Server System products to support the x64 platform, with both native x64 editions and 32-bit editions on the WOW64 subsystem. This approach demonstrates the flexibility of the x64 platform itself, allowing each product team to choose the right time to deliver native x64 functionality to their customers.

Today, there are native x64 versions of many Microsoft Server System products, including Windows Server 2003, Microsoft SQL Server 2005, Microsoft Exchange 2007 (x64-only), Microsoft Commerce Server 2007, Microsoft BizTalk Server 2006, and Microsoft Operations Manager.

Volume licensing customers are free to exchange their 32-bit version of Windows for the x64 version at any time, using their media kits.

Other customers should contact their OEM or regular fulfillment channels. They may be able to assist you with media.

Microsoft offers the following x64 editions of Windows Server 2003:

Windows Server 2003 x64 editions are licensed identically to their 32-bit counterparts.

Windows Server 2003 x64 editions are priced identically to their 32-bit counterparts and are available now. For more information, visit Windows Server 2003 Purchasing Options.

A small number of features are not included in x64 Windows, including DOS, POSIX, 16-bit support, and a few legacy networking protocols no longer in active use. However, we do not expect most customers to be affected by these differences. Based on customer feedback, we expect the initial x64 usage scenarios for Windows Server 2003 to be databases, business applications, Terminal Server, Active Directory, Internet Information Services (IIS), and technical computing.

Yes, they do apply. The unlimited virtualization rights apply to third-party virtualization solutions as well as Microsoft-supplied virtualization products and technologies. Accordingly, Datacenter Edition for Itanium-based systems can be used with a third-party Itanium-based hypervisor or other virtualization technology.

Microsoft identified a pre-existing Microsoft Itanium compiler issue that affects Windows Server 2003 SP1 for Itanium for systems running dual-core Intel Itanium 2 processors (code name "Montecito"), and SQL Server 2005 Analysis Services for dual-core Intel Itanium 2 processors (code name "Montecito"). The issue causes the machine state to be corrupted when a specific sequence of instructions is interrupted by a page fault. This issue doesn't exist in newer compiler distributions—such as Microsoft Visual Studio 2005, Windows Server 2008, and later compiler versions.

Microsoft proactively worked with Intel, fellow members of the Itanium Solutions Alliance, and the partner community to ensure that when Intel dual-core Itanium 2 platform-based solutions enter the market with Windows Server 2003 SP1 and SQL Server 2005 Analysis Services, customers have an exceptional experience. Microsoft issued a quick fix engineering package to partners for both the operating system (OS) and the compiler, along with a script so that partners can identify whether their code is impacted. Partners who develop and sell solutions using Windows Server 2003 SP1 for Intel's new dual-core Itanium 2 platform were asked to analyze their code and determine whether Microsoft's fixes need to be applied. Customers and partners also should read KB Article 924449 and KB article 924897 or search at http://support.microsoft.com/search. Microsoft has also issued a quick engineering fix for SQL Server Analysis Services. For the SQL Server hotfix, customers and partners also should read KB Article 925754.

Longer term, the OS and compiler fixes will be incorporated into Windows Server 2003 SP2, which is scheduled to be available in early 2007. The compiler used for Windows Server 2008 does not have this issue; however, applications and drivers created with compiler versions prior to Visual Studio 2005 may have this issue. In addition to the current hotfix, mainstream delivery of this fix to SQL Server 2005 Analysis Services will be delivered with SQL Server 2005 Service Pack 2, expected in the first quarter of 2007. The SQL Server 2005 main program is not affected.

Note: All other products with components that execute natively on Itanium platforms were checked for this issue and were found not to be impacted by the compiler problem.

Windows Server 2008 for Itanium-based systems is designed to offer customers high levels of performance, reliability, and scalability, and be the leading alternative platform for RISC-based UNIX servers. To address these needs, Windows Server 2008 for Itanium-based systems is specifically designed for scale-up database workloads and custom and line-of-business applications. As with Windows Server 2003, Windows Server 2008 for Itanium-based systems will continue to support client-side functionality for administration, management, and server utilities. This workload focus is consistent with the majority of current deployments of Windows Server on Itanium.

This announcement is specific to workload support for Windows Server 2008 on Itanium-based systems. Information about packaging plans for Windows Server 2008 will be available closer to the release of the server.

We're working with any and all database partners to enable support for Windows Server 2008. Windows Server 2008 for Itanium-based systems will include all the necessary foundation technologies to support database applications; business applications; and the ability for customers to design, deploy, and manage custom applications.

Microsoft is fully committed to the Itanium processor family and our customers using the Itanium architecture. The target workloads for Windows Server 2008 on Itanium-based systems meet the needs of an overwhelming majority of customers running Windows Server on Itanium-based systems today. Windows Server 2003 customers will continue to receive mainstream support through mid-2008 and extended support through mid-2013.

Yes. Microsoft is working with Intel's engineering team to ensure that the next version of IA-32EL runs with Windows Server 2008 for Itanium-based systems. Microsoft continues to recommend that primary applications requiring high performance and scalability use only native 64-bit code on Itanium-based systems. The Windows on Windows-64 (WOW64) subsystem and IA-32 Execution Layer may be used for running 32-bit applications that are not performance-critical, such as administration and utility applications.

There are existing tools and prescriptive guidance for smoothly migrating the File/Print and Active Directory workloads between servers (with the same or different processor architectures). For an example, see Microsoft File Server Migration Toolkit.

Windows Server 2008 for Itanium-based systems will support remote desktop for administration so that an IT professional can remotely administer and manage an Itanium-based server. However, Windows Server 2008 for Itanium-based systems cannot be deployed as a terminal server for use by multiple end users simultaneously.