Upgrade or Clean Install? Migrating to Windows Server 2008 - Page 2

 By Jabez Gan
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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.
This article was originally published on Nov 17, 2009
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