Multiple operating systems and file system compatibility

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

Multiple operating systems and file system compatibility

On computers that contain multiple operating systems, compatibility becomes more complex when you consider file system choices. The file systems to choose from are NTFS, FAT, and FAT32. (For more information, see Choosing a File System for the Installation Partition.)

NTFS is normally the recommended file system because it is more efficient and reliable, and supports important features including Active Directory and domain-based security. With NTFS, however, you need to take file system compatibility into account when considering whether to set up a computer to contain more than one operating system, because with Windows 2000 and the Windows Server 2003 family, NTFS has new features in addition to those in Windows NT. Files that use any new features will be completely usable or readable only when the computer is started with Windows 2000 or a product in the Windows Server 2003 family.

For example, a file that uses the new encryption feature will not be readable when the computer is started with Windows NT Server 4.0 or Windows NT 4.0 Server Enterprise Edition, which were released before the encryption feature existed.

For more information about features that affect file accessibility with products in the Windows Server 2003 family, see NTFS.


  • If you want to set up a computer with both Windows NT and Windows Server 2003 operating systems, and you want to have an NTFS partition, the only appropriate version of Windows NT is version 4.0 with the latest released Service Pack. Using the latest Service Pack maximizes compatibility between Windows NT 4.0 and Windows Server 2003. (Specifically, you must have Service Pack 5 or later.) Even the latest Service Pack, however, does not provide access to files using the new features in NTFS.

  • Using NTFS as the only file system on a computer that contains both Windows Server 2003 and Windows NT is not recommended. On these computers, a FAT partition containing the Windows NT 4.0 operating system ensures that when started with Windows NT 4.0, the computer will have access to needed files. In addition, if Windows NT is not installed on the system partition, which is almost always the first partition on the disk, it is recommended that the system partition also be formatted with FAT.

  • If you set up a computer so that it starts with Windows NT 3.51 or earlier on a FAT partition, and Windows Server 2003 on an NTFS partition, when that computer starts with Windows NT 3.51, the NTFS partition will not be visible. If you set up a computer this way, and the partition containing Windows NT 3.51 is not the system partition (which is almost always the first partition on the disk), the system partition must also be formatted with FAT.