Sams Teach Yourself MCSE Windows NT Server 4 in 14 Days
(Publisher: Macmillan Computer Publishing)
Author(s): David Schaer, et al
ISBN: 0672311283
Publication Date: 12/15/97

Sometimes FAT is not only good it is necessary. This is true for RISC computers. The system partition on RISC computers must be formatted with FAT because RISC computers boot from firmware and only initialize the drivers for FAT. Only the system partition on RISC-based computers must be FAT; the boot partition and partitions holding programs and data can be NTFS.

It might sound backward at first but NT boots from the system partition and then accesses the boot partition.

5.2.2. Long and Short FAT Filenames

Even though NT uses the same 16-bit FAT structure as DOS, it is capable of supporting long filenames. When a file is created on a FAT volume under NT both a long and short filename can be created. The short filename follows the standard 8.3 character naming conventions, whereas the long filename can be up to 256 characters including multiple spaces and periods. A file called It is great to be an MCSE created through NT on a FAT volume would have a short filename of ITISGR~1.

To display both long and short filenames from the command prompt type DIR /X.

The short filename would take up one directory entry and the long filename would take up two directory entries, one for every 13 characters. When the system is booted into DOS or when a DOS-based application is running in NT only the short filename is displayed.

DOS-based file repair utilities can incorrectly identify, or fail to identify, the long filenames and potentially corrupt data.

A short filename created automatically from a long filename can become difficult to properly identify. Creating the file It is green eggs and ham for breakfast in the same directory as It is great to be an MCSE would yield the short filename ITISGR~2 because the first six legal characters of both filenames are identical. Correlating the short filename to the long filename becomes more difficult following the fourth file that results in the same six-character short name. After the fourth iteration with the same results the system hashes characters to form a unique short name. If the file ITISGR~4 already existed, creating a file called It is Greek to me in the same directory would generate IT558B~1. Figure 5.1 demonstrates how short filenames can become cryptic.

Figure 5.1.  Short filenames can become cryptic.

You won’t be expected to be able to convert long filenames beyond the fourth iteration.

The ability to create long filenames on FAT volumes can be toggled off in the registry. By setting the value of the HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Control\Win31FileSystem subkey to 1, no additional long filenames could be generated on the FAT partitions.

5.2.3. FAT Deficiencies

One reason not to use FAT is because the FAT file system provides no form of local security. This means that you cannot selectively control access to files and directories on FAT partitions. Anyone who can log on to the machine locally will have full control of all files and directories. In addition, if you move files from an NTFS partition to a FAT partition, the file loses its permissions.

If you use compression methods, such as DoubleSpace and DiskSpace, NT will not be able to access the volume. When you move files from NTFS volumes to FAT volumes the files are no longer compressed.

5.3. NTFS Overview

The New Technology File System (NTFS) provides a significant improvement over the FAT file system. Under NT 4.0 NTFS provides both long and short filenames, security, file compression, speed, and recoverability. NTFS can be used exclusively on x86-based systems that will run only NT. RISC-based computers require at least a 2MB FAT partition to hold the boot files. Computers configured to dual boot DOS or Windows 95 must have at least one FAT volume.

Regardless of third-party products that might make NTFS volumes accessible under DOS, for purposes of the exam NT is the only operating system that can access NTFS volumes.

5.3.1. Long and Short NTFS Filenames

Long filename support is also provided on NTFS volumes. Like those on FAT partitions they can contain up to 256 characters and contain multiple spaces and periods.

Short filenames are generated automatically in order to allow DOS- and OS/2-based computers to access the same data. The short filenames are generated based on the same rules as those of FAT volumes. Although it is possible to disable the short filename generation on NTFS volumes this would render filenames created outside the 8.3 character structure invisible to DOS and OS/2 applications. Long filenames would be visible from a Windows 95-based computer from across the network.

The short filename generation would not enable DOS, Windows for Workgroups, or OS/2-based systems to access the NTFS partition on a local basis. Short names generated on FAT volumes would be locally accessible to these machines; the short filenames generated on NTFS partitions would be available only from across the network.

5.4. Managing NTFS Security

One of the major benefits of using NTFS is that it makes available the capability of local security. By implementing NTFS security you can control which users and groups have access to files and directories on local NTFS volumes.

Each of the objects (files, directories) that can be protected through local security will receive an access control list (ACL). The ACL contains the listing of users and groups allowed to access an object, along with the specific rights they have been permitted. The individual user and group names in the ACL are called access control entries (ACEs).

The local security provided by NTFS can augment the network security implemented on shared directories. Chapter 9, “NT Server 4.0 Network Clients,” details the integration of network security.