NTFS takes the best parts of both FAT and HPFS and improves upon those designs. From FAT, NTFS borrowed the "simplicity yields performance" philosophy. Performance increases when the number of disk transfers is minimized for common operations. From HPFS, NTFS borrowed techniques for speed and flexibility. For example, NTFS uses B-trees similar to those used by HPFS to maximize performance.
NTFS supports both long and short (eight-plus-three) filenames for compatibility with MS-DOS, HPFS, and other networked clients including OS/2, UNIX, AppleShare, and NFS. NTFS also provides for multiple extended attributes and allows future applications to define other extended attributes.
NTFS offers data security on fixed and removable hard disks, a feature important to corporate users and other power users.
For example, suppose Joe has a removable hard disk on his computer. That hard disk is formatted as an NTFS volume and has security permissions that allow access only to Joe and to one other coworker in his domain, Ann. Ann works at the company's branch office. Joe removes the disk from his computer and sends it to Ann, who installs it in her computer. When she accesses the files on the disk, since Ann's computer is in the same domain as Joe's, she sees that the security mechanisms within the domain for the NTFS volume are intact.
Note Be sure to shut down the system before removing a disk containing an NTFS volume.
In addition to these features, NTFS provides a recovery system that is more reliable than either FAT or HPFS, and NTFS meets POSIX requirements.
The following table summarizes key features of FAT, HPFS, and NTFS as implemented on Windows NT:
Table 5.3 Comparison of FAT, HPFS, and NTFS
FAT file system | HPFS | NTFS | |
Filename | Eight-plus-three ASCII characters [one period (delimiter) allowed]; on Windows NT 3.5, 255 Unicode characters [multiple periods (delimiters) allowed] | 254 bytes of double-byte characters [multiple periods (delimiters) allowed] | 255 Unicode characters [multiple periods (delimiters) allowed] |
File size | 232 bytes | 232 bytes | 264 bytes |
Partition | 232 bytes | 241 bytes | 264 bytes |
Maximum path length | 64; on Windows NT 3.5, no limit | No limit | No limit |
Attributes | Only a few bit flags, plus a few bytes of extended attribute information on Windows NT 3.5 | Bit flags plus up to 64K of extended-attribute information | Everything, including data, is treated as file attributes |
Directories | Unsorted | B-tree | B-tree |
Philosophy | Simple | Efficient on larger disks | Fast, recoverable, and secure |
Built-in security features | No | No | Yes |
The next section describes one other difference that distinguishes the FAT, HPFS, and NTFS file systems — that is, the way each file system ensures data integrity on the disk.