Windows 3.x and MS-DOS have always used the File Allocation Table (FAT) system; Windows 95 uses the extended FAT file system; while the Windows NT file system, while continuing to support 16-bit file systems, also supports two 32-bit file systems—Windows NT File System (NTFS) and High Performance File System (HPFS). These file systems each have their own advantages and disadvantages, and are suited to different application purposes.
I. File Allocation Table (FAT) System
The FAT file system began to be used in MS-DOS in 1982. The main advantage of the FAT file system is that it can be accessed by many operating systems, such as MS-DOS, Windows 3.x, Windows 95/98/2k, Windows NT, and OS/2. Also, for ARC-compatible computers, the primary partition must be formatted as a FAT partition. This partition only needs to be large enough to hold the files used to boot the machine, and will not be used to store data or other application files. Unfortunately, the FAT file system does not support long file names. When naming files, people are restricted by the 8.3 naming rule of an 8-character filename plus a 3-character extension. At the same time, the FAT file system cannot support advanced system fault-tolerance features, and it does not have internal security features.
II. Extended File Allocation Table (VFAT) System
In Windows 95, through extensions to the FAT file system, the long file name problem was properly solved, and this is what people call the extended FAT (VFAT) file system. In Windows 95, file names can be as long as 255 characters, so it is very easy to express a file's content through its name. But in order to remain compatible with MS-DOS and Win16-bit programs, it still retains extensions. At the same time it also supports file date and time attributes, preserving for each file these three date/time stamps: the file creation date/time, the date/time the file was last modified, and the date/time the file was last opened. Windows 95's VFAT file system and the Windows NT File System (NTFS) and High Performance File System mentioned below all support long file names. When using this feature, note the following points:
1. Since a long file name will occupy multiple directory entries, if long-file-name files are created in the root directory, this will affect the total number of files that can be stored in the root directory; if long-file-name files are created in subdirectories, they will take up some additional disk space.
2. Under MS-DOS, if a file name converted from a long file name is deleted or changed, the directory entries used by the long file name to store the name characters and the directory entries used to store the long file name's type information will be lost. If these directory entries are not specially handled, under ordinary MS-DOS they will become permanently unusable.
3. Some existing DOS-based disk management utilities (such as disk defragmentation tools, disk sector editors, and some disk backup software), when processing FAT entries, may damage the long-file-name entries in the FAT table, but the corresponding 8.3 file names will not be affected. Therefore, we should use the disk management utilities provided by Windows 95 as much as possible to perform file backup, recovery, and similar operations, so as to preserve long file names.
4. Some applications that run under MS-DOS and Windows 3.x cannot recognize long file names. If such applications are used to open a file with a long file name and then save it again, the long file name will be lost. Likewise, if a file with a long file name is copied into a system that does not support long file names, the long file name will also be lost.
III. Windows NT File System
NTFS supports all the advantages of Windows NT. The most important of these advantages is the security of Windows NT. Combined with the NTFS file system, it is possible to specify who can access a particular file or directory and what operations they can perform on it. When creating a file, you can tell Windows NT which users may read the file and which users may modify it; in addition, you can specify who may list the contents of a directory and who may add files under that directory. Even if a user knows the path to a file, access to files in the directory can still be denied. Only files in an NTFS partition have this capability, called discretionary access control.
The second advantage of NTFS is that it has advanced fault-tolerance capabilities. NTFS uses a technique called transaction logging to track modifications to the disk, so NTFS can recover from errors in a matter of seconds rather than the minutes or hours required by HPFS (depending on the size of the HPFS partition).
The third advantage of NTFS is that its files are less susceptible to viruses and system crashes. This resistance to interference comes directly from the high security performance of the Windows NT operating system. Even when FAT and NTFS coexist on the same disk, since the NTFS file system can only be recognized by Windows NT, ordinary viruses still have a hard time finding room to survive in the NTFS file system.
For large partitions, NTFS is more efficient than both FAT and HPFS. FAT and HPFS require more space than NTFS to store the information used by the file system to manage files and directories on the hard disk.
In addition, since the NTFS file system supports long file names, people no longer need to be restricted by the 8.3 naming rule when naming files, and can therefore give files names that reflect their meaning. NTFS supports downward compatibility and can even generate old-style short file names from new long file names. When a file is written to removable media (such as a floppy disk), it automatically uses FAT file names and the FAT file system.
In fact, the main weakness of NTFS is that it can only be recognized by Windows NT. The NTFS file system can access files in FAT and HPFS file systems, but its own files cannot be accessed by FAT and HPFS file systems, so compatibility is not especially good. But from the standpoint of network security, this limitation is also an advantage: it ensures that if other operating systems do not have Windows security control, their users cannot access files in NTFS partitions. In addition, if the boot drive (that is, drive C) uses the NTFS file system, the Flexboot option cannot be used, because the DOS system can only boot from drive C, but cannot boot from an NTFS drive. Relative to Windows NT, its boot partition can be FAT, NTFS, or HPFS. Finally, there is another problem: even when using Windows NT drivers, many backup utilities still have problems operating on NTFS partitions.
IV. High Performance File System
OS/2's High Performance File System (HPFS) mainly overcomes the shortcoming that the FAT file system is not suitable for high-end operating systems. HPFS supports long file names and has stronger error-correction capabilities than the FAT file system. Windows NT also supports HPFS, making the transition from OS/2 to Windows NT easier. HPFS and NTFS share many of the same features, including long file names, but its reliability is poorer and it is also lower-level.
The above four file systems are all supported by Windows. Generally speaking, users can make a comprehensive consideration from several aspects such as file system capabilities, file system security mechanisms, ease of use, and the corresponding hardware environment, and then choose either one file system alone or a combination of several of them, so that the system can work in its best state.
I. File Allocation Table (FAT) System
The FAT file system began to be used in MS-DOS in 1982. The main advantage of the FAT file system is that it can be accessed by many operating systems, such as MS-DOS, Windows 3.x, Windows 95/98/2k, Windows NT, and OS/2. Also, for ARC-compatible computers, the primary partition must be formatted as a FAT partition. This partition only needs to be large enough to hold the files used to boot the machine, and will not be used to store data or other application files. Unfortunately, the FAT file system does not support long file names. When naming files, people are restricted by the 8.3 naming rule of an 8-character filename plus a 3-character extension. At the same time, the FAT file system cannot support advanced system fault-tolerance features, and it does not have internal security features.
II. Extended File Allocation Table (VFAT) System
In Windows 95, through extensions to the FAT file system, the long file name problem was properly solved, and this is what people call the extended FAT (VFAT) file system. In Windows 95, file names can be as long as 255 characters, so it is very easy to express a file's content through its name. But in order to remain compatible with MS-DOS and Win16-bit programs, it still retains extensions. At the same time it also supports file date and time attributes, preserving for each file these three date/time stamps: the file creation date/time, the date/time the file was last modified, and the date/time the file was last opened. Windows 95's VFAT file system and the Windows NT File System (NTFS) and High Performance File System mentioned below all support long file names. When using this feature, note the following points:
1. Since a long file name will occupy multiple directory entries, if long-file-name files are created in the root directory, this will affect the total number of files that can be stored in the root directory; if long-file-name files are created in subdirectories, they will take up some additional disk space.
2. Under MS-DOS, if a file name converted from a long file name is deleted or changed, the directory entries used by the long file name to store the name characters and the directory entries used to store the long file name's type information will be lost. If these directory entries are not specially handled, under ordinary MS-DOS they will become permanently unusable.
3. Some existing DOS-based disk management utilities (such as disk defragmentation tools, disk sector editors, and some disk backup software), when processing FAT entries, may damage the long-file-name entries in the FAT table, but the corresponding 8.3 file names will not be affected. Therefore, we should use the disk management utilities provided by Windows 95 as much as possible to perform file backup, recovery, and similar operations, so as to preserve long file names.
4. Some applications that run under MS-DOS and Windows 3.x cannot recognize long file names. If such applications are used to open a file with a long file name and then save it again, the long file name will be lost. Likewise, if a file with a long file name is copied into a system that does not support long file names, the long file name will also be lost.
III. Windows NT File System
NTFS supports all the advantages of Windows NT. The most important of these advantages is the security of Windows NT. Combined with the NTFS file system, it is possible to specify who can access a particular file or directory and what operations they can perform on it. When creating a file, you can tell Windows NT which users may read the file and which users may modify it; in addition, you can specify who may list the contents of a directory and who may add files under that directory. Even if a user knows the path to a file, access to files in the directory can still be denied. Only files in an NTFS partition have this capability, called discretionary access control.
The second advantage of NTFS is that it has advanced fault-tolerance capabilities. NTFS uses a technique called transaction logging to track modifications to the disk, so NTFS can recover from errors in a matter of seconds rather than the minutes or hours required by HPFS (depending on the size of the HPFS partition).
The third advantage of NTFS is that its files are less susceptible to viruses and system crashes. This resistance to interference comes directly from the high security performance of the Windows NT operating system. Even when FAT and NTFS coexist on the same disk, since the NTFS file system can only be recognized by Windows NT, ordinary viruses still have a hard time finding room to survive in the NTFS file system.
For large partitions, NTFS is more efficient than both FAT and HPFS. FAT and HPFS require more space than NTFS to store the information used by the file system to manage files and directories on the hard disk.
In addition, since the NTFS file system supports long file names, people no longer need to be restricted by the 8.3 naming rule when naming files, and can therefore give files names that reflect their meaning. NTFS supports downward compatibility and can even generate old-style short file names from new long file names. When a file is written to removable media (such as a floppy disk), it automatically uses FAT file names and the FAT file system.
In fact, the main weakness of NTFS is that it can only be recognized by Windows NT. The NTFS file system can access files in FAT and HPFS file systems, but its own files cannot be accessed by FAT and HPFS file systems, so compatibility is not especially good. But from the standpoint of network security, this limitation is also an advantage: it ensures that if other operating systems do not have Windows security control, their users cannot access files in NTFS partitions. In addition, if the boot drive (that is, drive C) uses the NTFS file system, the Flexboot option cannot be used, because the DOS system can only boot from drive C, but cannot boot from an NTFS drive. Relative to Windows NT, its boot partition can be FAT, NTFS, or HPFS. Finally, there is another problem: even when using Windows NT drivers, many backup utilities still have problems operating on NTFS partitions.
IV. High Performance File System
OS/2's High Performance File System (HPFS) mainly overcomes the shortcoming that the FAT file system is not suitable for high-end operating systems. HPFS supports long file names and has stronger error-correction capabilities than the FAT file system. Windows NT also supports HPFS, making the transition from OS/2 to Windows NT easier. HPFS and NTFS share many of the same features, including long file names, but its reliability is poorer and it is also lower-level.
The above four file systems are all supported by Windows. Generally speaking, users can make a comprehensive consideration from several aspects such as file system capabilities, file system security mechanisms, ease of use, and the corresponding hardware environment, and then choose either one file system alone or a combination of several of them, so that the system can work in its best state.
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