Determining How Many Operating Systems to Install

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Determining How Many Operating Systems to Install

You can install multiple operating systems on a computer so that the user can choose the operating system to use each time the user starts the computer. You can also specify an operating system as the default that starts when the user makes no selection.

Important

If you install Windows Vista and any other operating system on a computer, you must install Windows Vista on a separate partition. Installing Windows Vista on a separate partition ensures that it will not overwrite files used by the other operating system.

Installing multiple operating systems on a computer has some drawbacks, however. Each operating system uses disk space, and compatibility issues (especially between file systems) can be complex. Also, you cannot use dynamic disks with certain operating systems. Only Windows 2000, Windows XP Professional, and Windows Vista can access a dynamic disk.

Converting a basic disk to a dynamic disk that contains multiple installations of Windows Vista, Windows XP Professional, or Windows 2000 can cause startup problems.

Note

To ensure that you can always start the computer, despite driver or disk problems, consider the disaster-recovery features available in Windows Vista. Safe Mode allows Windows Vista to restart with default settings and the minimum number of drivers. The computer will start even if a new driver causes a problem. With this and other disaster-recovery features, you do not need more than one operating system as a safeguard against system problems.

When you perform a clean installation of Windows Vista (not an upgrade), by default the installation is put on a partition on which no other operating system is located. You can specify a different partition when you run Setup.

Before setting up a computer that has more than one operating system, review the following restrictions.

For computers on which you want to install MS-DOS and Windows Vista:

  • Install MS-DOS first. Otherwise important files needed to start Windows Vista can be overwritten.
  • Install each operating system on its own partition, and then install the applications used with each operating system on the same partition. If you intend to run an application on both operating systems, install it on both partitions.
  • Format the system partition as FAT.

For computers on which you want to install Windows 95 and Windows Vista:

  • Install Windows 95 first. Otherwise important files needed to start Windows Vista can be overwritten.
  • Install each operating system on its own partition, and then install the applications used with each operating system on the same partition. If you intend to run an application on both operating systems, install it on both partitions.
  • Format the system partition as FAT. (For Windows 95 OSR2, the primary partition must be formatted as FAT or FAT32.)
  • Compressed DriveSpace or DoubleSpace volumes are not available while you run Windows Vista. It is not necessary to uncompress DriveSpace or DoubleSpace volumes that you access only from Windows 95.

For computers on which you want to install Windows 98 or Windows Me and Windows Vista:

  • Install each operating system on its own partition, and then install the applications used with each operating system on the same partition. If you intend to run an application on both operating systems, install it on both partitions.
  • Format the system partition as FAT or FAT32.
  • Compressed DriveSpace or DoubleSpace volumes are not available while you run Windows Vista. It is not necessary to uncompress DriveSpace or DoubleSpace volumes that you access only from Windows 98.

For computers on which you want to install Windows NT 4.0 and Windows Vista:

  • Make sure that Windows NT 4.0 has been updated with the latest service pack.
  • Install each operating system on its own partition, and then install the applications used with each operating system on the same partition. If you intend to run an on both operating systems, install it on both partitions.
  • Using NTFS as the only file system on a computer that contains both Windows Vista and Windows NT is not recommended.
  • Do not install Windows Vista on a compressed volume unless the volume was compressed by using the NTFS compression feature.
  • If the computer is part of a domain, use a unique computer name for each installation.

For computers on which you want to install Windows 2000, or Windows XP Professional, and Windows Vista, or multiple Windows Vista partitions:

  • Install each operating system on its own partition, and then install the applications used with each operating system on the same partition. If you intend to run an application on both operating systems, install it on both partitions.
  • On a computer on which you install multiple Windows Vista partitions, you can install any product in the Windows Vista product family. For example, you can install Windows Vista on one partition and Microsoft® Windows® XP Home Edition on another.
    • Because Windows XP Home Edition does not support dynamic disks, you must use basic disks on computers that multiple-boot Windows Vista and Windows XP Home Edition.
    • If the computer participates in a domain, use a different computer name for each installation. Because a unique security identifier (SID) is used for each installation of Windows Vista on a domain, the computer name for each installation must be unique, even for multiple installations on the same computer.
    • If you use Encrypting File System (EFS), ensure that encrypted files are available from each of the installations.

Multiple Operating Systems and File System Compatibility

For Windows-based computers, the available file systems are NTFS, FAT, and FAT32.

The version of NTFS included in Windows 2000, Windows XP Professional, and Windows Vista, has new features that are not available for Windows NT. You might have full access to files that use new features only when the computer is started by using Windows Vista, Windows 2000, or Windows XP Professional. For example, a file that uses the new encryption feature is not readable when the computer is started with Windows NT 4.0, which was released before the encryption feature existed.

To set up a computer that has an NTFS partition, to run Windows NT and Windows Vista you must use Windows NT 4.0 with the latest released Service Pack. Using the latest Service Pack maximizes compatibility between Windows NT 4.0 and the NTFS enhancements in Windows Vista. Specifically, Service Pack 4 and later Service Packs provide this compatibility in file systems. Even the most recent service pack, however, does not provide access to files using later features in NTFS.

Using NTFS as the only file system on a computer that contains both Windows XP Professional and Windows NT is not recommended. On these computers, a FAT partition ensures that the computer has access to needed files when it is started with Windows NT 4.0.

If you set up a computer with Windows NT Workstation 3.51 or earlier on a FAT partition, and Windows Vista on an NTFS partition, the NTFS partition is not visible while you run Windows NT Workstation 3.51.

Multiple Operating Systems and EFS

If you configure a computer so that it contains Windows 2000 or Windows XP Professional and Windows Vista, or contains multiple Windows Vista partitions, you must take certain steps to use EFS so that encrypted files are readable between the different installations. Use either of the following approaches:

  • Ensure that all the installations are in the same domain and that the user has a roaming profile.
  • Export the user's file encryption certificate and associated private key from one installation and import it into the other installations.