Upgrade or Clean Install? Migrating to Windows Server 2008

Monday Nov 16th 2009 by Jabez Gan
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With Windows Server 2008 R2, Microsoft has dropped development of 32-bit server architectures. Jabez Gan spells out your options for migrating existing 32- or 64-bit hardware to the new release.

This article is the first of a 4-part series on the deployment of Windows Server 2008 R2. We'll talk about the options available to move to Windows Server 2008 R2, and what planning and considerations are required for a successful migration.

The Rise of 64-Bit Operating System

As 64-bit hardware is becoming more common due to an increase of memory usage and processing demand in applications, it would be a logical step to focus development solely on 64-bit operating systems instead of supporting both 32-bit and 64-bit architectures. 64-bit architectures allow for more than 4GB of address space for operating system and applications, and they help speed up processing of scientific applications that do a lot of complex numerical analysis. On the business side, the demand for 64-bit hardware is increasing, thus it would be beneficial to focus on developing a better product for the 64-bit customers.

Due changing industry trends, starting with Windows Server 2008 R2, Microsoft has stopped developing a 32-bit Windows Server platform for the public. Yes, you heard it right, but don't get this confused this with Windows 7. Microsoft's latest client-side operating system has both 32-bit and 64-bit flavors, allowing Windows 7 to be installed on older hardware which supports only 32-bit architecture.

What are the implications for IT? Many admins are wondering, "what about the legacy software that runs perfectly fine on x86 platform? What about the old but faithful x86 hardware?" We will be covering these questions later in this section.

Decision Matrix – Clean or Upgrade

With the shift to 64-bit operating systems, IT departments will need to have a different strategy for managing their IT infrastructures. If a server reaches its capacity, do you cluster a new machine, or do you upgrade the server operating system? If the existing server is running with a 32-bit operating system, clean installation is the only option. It is not possible to upgrade the operating system from a 32-bit OS to a 64-bit OS (or vice versa).

The following table will give you an idea of when to do a clean installation of Windows Server 2008 R2, and when to do an upgrade.

Clean/Migration Upgrade
x86 (32-bit) OS yes no
x86 (64-bit) OS yes yes
Legacy Application test or consult developer
32-bit Hardware yes no
64-bit Hardware yes yes
System volume:
<14GB free space
yes no
Table 1: Decision Matrix: Clean/Migration or Upgrade

Upgrading From a 32-Bit to 64-Bit Operating System

As shown in table 1 above, if the installed operating system is a 32-bit version, it will not be possible to do an upgrade to Windows Server 2008 R2. Cross-architecture, in-place upgrades (for example, x86 to x64) are not possible. In this scenario, the only option is to do a clean installation and migration of the applications and settings to a clean installation Windows Server.

Legacy Applications

If you have legacy applications, it is very important to have them tested thoroughly in a testing environment. Most 32-bit legacy applications should work when deployed in Windows Server 2008 R2, but it is always wise to contact the software developer for compatibility questions. However, 16-bit legacy applications will not work in Windows Server 2008 R2, as 16-bit applications can't be installed on a 64-bit operating system.

64-Bit Hardware

The latest hardware on the market is 64-bit ready, thus it shouldn't be an issue when installing Windows Server 2008 R2. But if you are unsure if your existing hardware is 64-bit capable, you can run the SecurAble tool from Gibson Research Corporation. SecurAble will report "64 Maximum Bit Length" for 64-bit capable hardware.

Minimum Free Space For System Volume

Another factor in deciding whether a system can be upgraded is the system volume's free space. In order to do an upgrade, the system volume needs to have at least 14GB of free space. The system volume is the hard disk partition that stores the Windows files and folders.

Hardware Drivers

The last determining factor is to ensure that the hardware is tested and supported by Microsoft. It's wise to crosscheck the existing hardware with Windows Server Catalog to make sure you won't face the unpleasant surprise that there is no 64-bit driver for your hardware.

Clean Installation or Upgrade? Pros and Cons?

If upgrade is possible, you might need to devote additional thought to the pros and cons of either going ahead with the upgrade, or doing a clean installation. Table 2 below will break down on the pros and cons and help you ensure a smooth deployment.

Pros Cons
Clean Installation + Migration Easier to troubleshoot installation failures. Requires migration of applications.
Predictable Time consuming
Upgrade Straightforward Harder to troubleshoot installation failures.
Less time consuming Unpredictable.
Table 2: Pros and Cons of a Clean Installation/Upgrade

As shown in table 2 above, determining whether to do a clean installation or upgrade is based on time needed and complexity. Upgrading might save a lot of time, but if issues arise it will be harder to troubleshoot and create longer downtime. Clean installation is time consuming as application data and services will need to be migrated. It is not relatively complex, but the migration process is also relatively predictable.

What's Next?

For the next part of this series, we will be discussing migration planning. Migration involves the transfer of server settings and roles from an old server to a new server, and there are many factors contributing to the success of a migration. We'll be covering those key factors to help you plan a successful migration.


Jabez Gan is a Microsoft Most Valuable Professional (MVP) and is currently the Senior Technical Officer for a consulting company that specializes in Microsoft technologies. His past experience includes developing technical content for Microsoft Learning, Redmond, Internet.com and other technology sites, and deploying and managing Windows Server Systems. He has spoken at many technology events, including Microsoft TechEd Southeast Asia.
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