Introduction

A computer can be configured to let you choose between two or more operating systems each time you restart the computer. For example, you could set up a server to run Windows® 2000 Server most of the time but allow it to sometimes run Windows NT® Server 4.0 in order to support an older application. With multibooting, you can choose which operating system to run or specify a default OS if no selection is made during the restart process.

Before using the multibooting feature, consider the tradeoffs: each operating system uses valuable disk space, and file system compatibility can be complex if you want to run Windows 2000 on one partition and Windows NT Server 4.0 or an earlier OS on another partition. In addition, dynamic disk format introduced in Windows 2000 does not work with earlier operating systems. However, multibooting capabilities are a valuable feature providing the single-machine flexibility not only to run earlier operating systems but also experience the advances in the next version of the operating system, now codenamed Whistler.

This page provides an overview of multibooting beginning with guidelines for multibooting with Windows 2000 and Whistler. It also addresses multibooting issues for running Windows 2000 with earlier operating systems including Windows NT 4.0, Windows 9x, and MS-DOS®. Each section includes a checklist summary for easy reference.

Before installing Windows 2000 and Whistler on the same machine, you need to prepare your system with different partitions (a process that divides a hard disk into separate sections that can be formatted for use by a file system. Partitions typically have different drive letters such as C or D).

One OS per partition
It’s important to install each operating system on a different partition and install the applications used with each operating system on the same partition as the OS. If an application is used with two different operating systems, install it on two partitions. Placing Windows 2000 or Whistler in a separate partition ensures that it will not overwrite crucial files used by the other operating system.

Install Latest OS Last
In general, you should install the most recent OS last—after you have installed all other operating systems on the target computer. In this case, you should install Windows 2000 and then install Whistler.

Unique Computer Name
You can set up a server so that it has multiple installations of Windows 2000 (using any Windows 2000 product) or Whistler (using any Whistler product) on multiple partitions. However, you must use a different computer name for each installation if the computer participates in a Windows 2000 or Whistler domain. Because a unique security identifier (SID) is used for each installation of Windows 2000 or Whistler on a domain, the computer name for each installation must be unique—even for multiple installations on the same computer.

Multiple Operating Systems and the Encrypting File System
If you set up a server so that it contains Windows 2000 and Whistler, or contains multiple Whistler partitions, and you want to use the encrypting file system (EFS) on the computer, you must take certain steps. These steps make encrypted files readable between the different installations. One approach is to ensure that all the installations are in the same domain and that the user of these installations has a roaming profile. Another approach is to export the user's file encryption certificate and associated private key from one installation and import it into the other installations.

For more information, see the following Help topics: EFSM Roaming user profiles Importing and exporting certificates

Checklist Summary
To configure a computer containing Windows 2000 and Whistler, review the following guidelines:

Setting up a computer to run Windows 2000 as well as an earlier operating system such as Windows NT Server 4.0 requires addressing compatibility issues among different file systems: NTFS, FAT, and FAT32.

Normally, NTFS is the recommended file system because it supports important features, including the Active Directory™ service and domain-based security. However, if your computer will sometimes run an earlier operating system such as Windows NT Server 4.0 and sometimes run Windows 2000 or Whistler, you will need to have a FAT or FAT32 partition as the primary (or startup) partition on the hard disk. This is because earlier operating systems, with one exception, can't access a partition if it uses the latest version of NTFS. The one exception is Windows NT version 4.0 with Service Pack 4 or later, which has access to partitions with the latest version of NTFS, but with some limitations.

Even the latest Service Pack does not provide access to files using the new features in NTFS. Windows NT 4.0 cannot access files that have been stored using NTFS features that did not exist when Windows NT 4.0 was released. For example, a file that uses the new encryption feature won’t be readable when the computer is started with Windows NT 4.0 Workstation, Windows NT Server 4.0 or Windows NT 4.0 Enterprise Edition, which were released before the encryption feature existed.

For more information see the following Help topic:

Note: If you set up a computer so that it starts with Windows NT 3.51 or earlier on a FAT partition, and Windows 2000 Server on an NTFS partition, when that computer starts with Windows NT 3.51, the NTFS partition will not be visible.

Checklist Summary
To configure a computer containing Windows NT 4.0 and Windows 2000, review the following guidelines:

As explained above you need to address file system compatibility to ensure a multibooting configuration with these earlier operating systems and Windows 2000. Remember to install the latest operating system last otherwise important files may be overwritten.

Checklist Summary
To configure a computer containing Windows 2000 and Windows 9x or MS-DOS, review the following guidelines:

On computers that contain MS-DOS and Windows 2000:

On computers that contain Windows 95 and Windows 2000:

On computers that contain Windows 98 and Windows 2000: