We all want to get the most power from our computing resources, and 64-bit versions of Windows Server are becoming more common in the data center. This list describes some factors to keep in mind with 64-bit Windows Server so that you can gain its benefits and avoid potential problems.
Note: This information is also available as a PDF download.
#1: Drivers are no fun
It's important to correctly manage certain drivers, namely RAID controllers. They're not impossible to manage, but they require additional planning compared to your familiar 32-bit management practices. Always check the drivers that are available for all hardware you are using on your servers to see whether a 64-bit version is available.
#2: Some BIOS settings disable 64-bit capabilities
Most current Dell PowerEdge and HP ProLiant systems have the BIOS settings configured so that the 64-bit setting is disabled. This is usually referred to as a "virtualization technology" setting in the BIOS. Having this setting correct will enable your installation of a 64-bit aware operating system. Windows server installations will not proceed if a 64-bit processing environment is not found.
Note that some installations are 32-bit and 64-bit aware. An example would be VMware's ESX operating system, which will install on both 32-bit and 64-bit processor systems. Make sure you have the setting correct upon operating system installation. Also, be mindful that if you get a motherboard replaced or a BIOS flash, this setting may revert to the default.
#3: Task Manager distinguishes environments
You will quickly notice in the Windows Task Manager that 32-bit processes are denoted differently from 64-bit ones. The 32-bit processes have a "*32" placeholder at the end of the process name listed, although a running process won't have a "*32" attached to the name of the file. Some 64-bit processes may have a "64" in the name somewhere.
#4: Service pack management requires a different approach
The 64-bit versions of Windows Server 2003 provide different service pack releases. Depending on your update management strategy, the 64-bit version updates will need to be incorporated and tested accordingly.
#5: Windows 64-bit computing isn't a requirement
Generally speaking, Windows 64-bit computing is not required. However current server hardware supporting 64-bit processing offers greater performance than its 32-bit mode counterpart. Some Microsoft solutions, like Exchange 2007, are available only in 64-bit editions. High CPU requirement systems should use a 64-bit version of the operating system.
#6: Installation media management differsThe 64-bit versions of Windows are different media from 32-bit versions, which is fairly straightforward when purchasing retail versions of the operating system software. But if you have access to the Microsoft Volume Licensing Services (MVLS) with the online distribution mechanism, be sure to select the correct operating system version. The most current popular server versions, Windows Server 2003 Standard and Enterprise R2, are displayed as the default choices. To see the full inventory of operating systems, expand the tree (Figure A).
When you select your edition, you can select the 32-bit or 64-bit version for download. (Figure B).
#7: 64-bit Itanium processors lack support for client systems
The Itanium processor line is used much less frequently than the AMD64 and Intel 64 offerings. Microsoft still provides Windows Server 2003 Enterprise Edition for the Itanium processor platform. But Itanium support is not available on client operating systems, such as Windows XP and Vista. Intel 64 and AMD64 are available on the client platform. From a hardware perspective, you won't want to run a client operating system on an Itanium class system.
This alone is not directly significant, but it limits the inventory of compatible software available for the platform. Using Windows Server 2003, Vista, or XP on the Intel 64 or AMD64 platforms does not present as large a limiting factor. In situations where an issue is hard to identify, the Itanium version may be viewed as an "out" in trying to diagnose the error.
#8: 64-bit versions may add to your support overhead
Being on a 64-bit version of Windows does not inherently make your support situation more difficult, but it's something to keep in mind. From an internal support standpoint, it is unlikely that all of your Windows server systems will be at a 64-bit version -- so you have to realize that you'll be supporting an additional platform. My current stance is to use a 64-bit version of the Windows Server series as required, such as for high CPU requirements or core application requirements, while maintaining the 32-bit versions for most systems.
#9: You need to know your limits
Microsoft publishes a list of limits for 64-bit versions of Windows. This is a good place to start if you are new to 64-bit computing. The main takeaway is that you can't mix processes between 32-bit and 64-bit versions. You'll find the list in the Microsoft online knowledge base.
#10: 64-bit versions and 16-bit apps don't mix
If any 16-bit applications are needed, you shouldn't consider the 64-bit versions of Windows Server products. You can, however, configure your 64-bit capable equipment to run in 32-bit mode. This configuration can permit the legacy applications to function correctly.
Rick Vanover works for Safelite Auto Glass (Belron US) in Columbus, OH. There, he is part of a team of IT professionals providing central Windows-based server administration. He previously worked for Dematic Corp (formerly Siemens L&A, Siemens Dematic, Rapistan) in various capacities, deploying custom software solutions to the material-handling industry using a mix of current hardware and software products. You can reach Rick at firstname.lastname@example.org.