NTFS File System provides a combination of performance, reliability, and compatibility. All of these is not found in either FAT or HPFS. It is designed to quickly perform standard file operations such as read, write, and search. Even advanced operations such as file–system recovery on a very large hard disk management.
Server File System
It also includes security features required for file servers and high-end personal computers in a corporate environment. This file system supports data access control and ownership privileges that are important for the integrity of corporate data . while directories shared by a Windows NT Server are assigned particular permissions whether they are shared or not. NTFS is the only file system on Windows NT that allows you to assign permissions to individual files.
NTFS has a simple, yet very powerful design. From the file system’s perspective, everything on the NTFS volume is a file or part of a file. Every sector on an NTFS volume that is allocated belongs to some file .even the file system metadata(information that describes the file system itself) is a part of a file. This attribute-based file system supports object-oriented applications by treating all files as objects that have user-defined and system-defined attributes.
Master file table
Each file on an NTFS volume is represented by a record in a special file called the master file table (MFT). NTFS reserves the first 16 records of the table for special information. The first record of this table describes the master file table itself. Followed by an MFT mirror record. If the first MFT record is corrupted, NTFS reads the second record to find the MFT mirror file. Whose first record is identical to the first record of the MFT. The locations of the data segments for both the MFT and MFT mirror file are recorded in the logical center of the disk.
Log File for Recovery
The third record of the MFT is the log file, used for file recovery. The seventeenth and following records of the master file table are for each file and directory (also viewed as a file by NTFS) on the volume.
The master file table allocates a certain amount of space for each file record. The attributes of a file are written to the allocated space in the MFT. Small files and directories (typically 1500 bytes Or smaller) an entirely be contained within the master file table record.
Faster than FAT
This design makes file access very fast. Consider, for example, the FAT file system, which uses a file allocation table to list the names and addresses of each file. FAT directory entries contain an index into the file allocation table. When you want to view a file, FAT first reads the file allocation table and assures that it exists. Then FAT retrieves the file by searching the chain of allocation units assigned to the file. With NTFS as soon as you look up the file, it’s there for you to use.
Directory records are housed within the master file table just like file records. Instead of data, directories contain index information. Small directory records reside entirely within the MFT structure. Large directories are organized into B-trees. Having recorded with pointers to external clusters containing directory entries that could not be contained within the MFT structure.
NTFS File Attributes
NTFS views each file (or directory) as a set of file attributes. Elements such as the file’s name. Its security information. And even its data are all file attributes. Each attribute is identified by an attribute type code and, optionally, an attribute name.
When a file ’s attributes can be written within the MFT file record, they are called resident attributes. For example, information such as filename and time stamp are always included in the MFT file record. When a file is too large to fit all of its attributes in the MFT file record, some of its attributes are nonresident.
The nonresident attributes are allocated one or more runs of disk space elsewhere in the volume. A run of disk space is a contiguous linear area o the disk. In general, all attributes can be referenced as a stream of bytes whether they are resident or nonresident.