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Windows Server 2003, Enterprise Edition: Upgrade or new installation?

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Windows Server 2003, Enterprise Edition: Upgrade or new installation?

After you have reviewed System Requirements and Hardware Compatibility and Important files to review, and before you run Setup, you will need to determine whether to upgrade or to perform a new installation. Upgrading is either replacing Windows NT 4.0 (with Service Pack 5 or later) or Windows 2000 with a product in the Windows Server 2003 family. In contrast, installing means completely removing the previous operating system, or installing a product in the Windows Server 2003 family on a disk or disk partition with no previous operating system.

If you have already decided whether to upgrade or to perform a new installation, see Checklist: Performing an upgrade or Checklist: Performing a new installation.

The following lists describe points to consider when deciding between an upgrade and a new installation.

Points to consider for an upgrade

  • With an upgrade, configuration is simpler and your existing users, settings, groups, rights, and permissions are retained.

  • With an upgrade, you do not need to reinstall files and applications. As with any major changes to the hard disk, however, we recommend that you back up the disk before beginning an upgrade.

  • Before planning to perform an upgrade, see "Operating systems from which you can upgrade" later in this topic.

  • If you are upgrading in a domain that includes domain controllers running Windows 2000, be sure to read Upgrades in a domain containing Windows 2000 domain controllers.

  • If you are upgrading in a domain where all domain controllers run Windows NT 4.0, be sure to read Upgrades in a Windows NT 4.0 Domain.

  • If you want to upgrade and then use the same applications as before, be sure to review applications information in Relnotes.htm (in the \Docs folder on the product CD). Also, for the most recent information on compatible applications for products in the Windows Server 2003 family, see the software compatibility section of the Microsoft Web site.

Points to consider for a new installation

  • If you reformat your hard disk and then perform a new installation, the efficiency of your disk might improve (compared to not reformatting it). Reformatting also gives you the opportunity to modify the size or number of disk partitions, to make them match your requirements more closely.

  • If you want to practice careful configuration management, for example for a server where high availability is important, you might want to perform a new installation on that server instead of an upgrade. This is especially true on servers on which the operating system has been upgraded several times in the past.

  • It is possible to install more than one operating system. Setting up the computer this way, however, presents complexities because of file system issues. For more information, see Deciding Whether a Computer Will Contain More Than One Operating System.


    • Do not install Windows Server 2003 on a compressed drive unless the drive was compressed with the NTFS file system compression utility. Uncompress a DriveSpace or DoubleSpace volume before running Setup on it.
  • If you used Windows NT 4.0 to create a volume set, mirror set, stripe set, or stripe set with parity, and you want to run Setup for Windows Server 2003 on that computer, you must prepare the disk set first. For details, see Working with volume, mirror, or stripe sets or stripe sets with parity.

Operating systems from which you can upgrade

If you upgrade, Setup automatically installs Windows Server 2003 into the same folder as the currently installed operating system. You can upgrade to Windows Server 2003, Standard Edition, and Windows Server 2003, Enterprise Edition, from the following versions of Windows:

  • Windows NT Server 4.0 with Service Pack 5 or later

  • Windows NT Server 4.0, Terminal Server Edition with Service Pack 5 or later

  • Windows NT Server 4.0, Enterprise Edition with Service Pack 5 or later

  • Windows 2000 Server

  • Windows 2000 Advanced Server


    • You can also upgrade from Windows Server 2003, Standard Edition to Windows Server 2003, Enterprise Edition.

    • If you have a version of Windows NT earlier than Windows NT 4.0, you cannot upgrade directly to a product in the Windows Server 2003 family. You must first upgrade to Windows NT 4.0 and apply Service Pack 5 before upgrading to a product in the Windows Server 2003 family.

    • If you have servers or client computers that run Windows NT 3.51, we recommend that you install or upgrade to a newer operating system on all these computers, or retire them from operation. If you have more than one domain, you must upgrade domain controllers running Windows NT 3.51 for reliable logon validation. In any case, upgrading or retiring computers running Windows NT 3.51 strengthens security and reduces the number of version differences between computers, simplifying management and troubleshooting.

    • You cannot upgrade from an earlier version of a Windows server operating system to an Itanium-based or x64-based version of a Windows server operating system.