What are the advantages and disadvantages of the file system format?

1. What is NTFS-New (N) Technology (T) File (F) System?

To understand NTFS, you must first understand FAT. FAT (file allocation table) means "file allocation table". For us, its significance lies in the management of hard disk partition. FAT 16, FAT32 and NTFS are the three most commonly used file systems at present.

FAT 16: DOS and Windows 95 used the FAT 16 file system, but now commonly used Windows 98/2000/XP systems all support the FAT 16 file system. It can manage up to 2GB of partitions, but each partition can only have up to 65525 clusters (clusters are the configuration units of disk space). With the increase of hard disk or partition capacity, the space occupied by each cluster will become larger and larger, resulting in the waste of hard disk space.

FAT32: With the appearance of large-capacity hard disks, FAT32 has become popular since Windows 98. It is an enhanced version of FAT 16, which can support the partition with a maximum of 2TB(2048G). The cluster used by FAT32 is smaller than FAT 16, which effectively saves hard disk space.

NTFS: A disk format supported by a series of operating systems of Microsoft Windows NT kernel, specially designed for network and disk quota, file encryption and other management security features. With the popularity of Windows 2000/XP with NT as the kernel, many individual users began to use NTFS. NTFS also stores data files in clusters, but the size of clusters in NTFS does not depend on the size of disks or partitions. The reduction of cluster size not only reduces the waste of disk space, but also reduces the possibility of disk fragmentation. NTFS supports file encryption management function, which can provide users with a higher level of security.

2. What system can support NTFS file system?

Only Windows NT/2000/XP can recognize the NTFS system, while Windows 9x/Me and DOS cannot support and recognize NTFS-formatted disks. Because DOS system does not support NTFS system, it is best not to make C: disk into NTFS system, which is convenient for the system to be repaired under DOS system after it crashes.

NTFS and operating system support are as follows:

fat 16 windows 95/98/me/nt/2000/XP UNIX、linux、dos

FAT32 windows 95/98/me/2000/xp

NTFS windows nt/2000/xp

3. Do we need NTFS?

Windows 2000/XP is backward compatible in the file system, and can well support FAT 16/FAT32 and NTFS, among which NTFS is a special format of Windows NT/2000/XP, which can fully and effectively use disk space, support file-level compression, and make files more secure. If only Windows 2000/XP is installed, NTFS file system is recommended. If it is a multi-boot system, the system disk (disk C) must be FAT 16 or FAT32, otherwise multi-boot is not supported. Of course, the file system of other partitions can also be NTFS.

1、fat 16

For computer veterans, this hard disk partition format is the most familiar, and most of us know and step into the computer threshold through this partition format. It adopts 16 bit file allocation table, and the maximum partition it can support is 2gb. It is the most widely used and supported disk partition format in the current operating system. Almost all operating systems support this format, from dos, win 3.x, win 95, win 97 to win 98, windows nt, win 2000/XP, and even the popular linux supports this partition format.

But the fat 16 partition format has one of the biggest shortcomings, that is, the actual utilization efficiency of hard disk is low. Because in dos and windows systems, the allocation of disk files is based on clusters, and a cluster is only allocated to one file, no matter how big this file accounts for the capacity of the whole cluster. Moreover, the size of each cluster is determined by the size of the hard disk partition. The larger the partition, the larger the cluster. For example, if the 1gb hard disk is only divided into one area, the cluster size is 32kb. That is to say, even if a file is only 1 byte long, it will occupy 32kb of hard disk space when it is stored, and all the remaining space will be idle, which will lead to a great waste of disk space. The larger the partition supported by fat 16, the greater the capacity of each cluster on the disk and the greater the waste. Therefore, with the increasing capacity of mainstream hard disks, this shortcoming has become more and more prominent. In order to overcome this weakness of fat 16, Microsoft introduced a brand-new disk partition format fat32 into win 97 operating system.

FAT is the file allocation table, which is often called FAT 16. It is a hard disk partition format widely used since DOS and Windows 3.x, and it is a traditional 16-bit file system. Excellent compatibility, various versions of DOS, Windows, Windows NT and other operating systems support FAT 16. It is relatively fast and consumes less CPU resources, so it is still a common partition format for hard disks of various machines. However, the traditional FAT 16 does not support long file names, which is limited by 8+3, that is, 8-character file names plus 3-character extensions. The maximum size of a single partition is 2GB, and the maximum capacity of a single hard disk generally cannot exceed 8GB, so if the hard disk capacity exceeds 8GB, the space above 8GB will be wasted because it cannot be used. When the partition size is 2GB, the size of a single "cluster" (the smallest unit of disk capacity) is 16KB. When the number of files is huge, it will leave a lot of unused space in vain. The deleted files cannot be recovered by using the FAT format in Windows NT. In addition, this file system is vulnerable to virus attacks because of its good compatibility and poor security.

Starting from Windows 95, Microsoft introduced the extended file allocation table VFAT, which broke through the limit of 8+3 and supported long file names with a maximum length of 255 characters, including suffixes. File names can contain multiple spaces or suffixes. Other advantages and disadvantages are basically the same as FAT 16.

2、fat32

FAT32 is a 32-bit file system compatible with 16 bits, which was introduced by Windows 95 OSR2. The biggest feature is to use smaller clusters (each cluster is only 4KB) to allocate file units, which greatly improves the utilization rate of hard disk space and reduces waste. The maximum capacity of a single hard disk reaches 2TB( 1TB= 1024GB), which provides convenience for users with a large number of hard disks. It supports long file names and can run various versions of DOS and Windows 95-2000 well, but the system overhead is higher than FAT 16. The security of this file system is still poor; FAT32 can be compatible with FAT 16, but it cannot access NTFS partition. For text files generated by editing software such as Word, files created on FAT32 machine can only be opened on FAT 16 computer if they are saved in "plain text" format. Windows 95 OSR2 and Windows 98 provide one-way conversion from FAT 16 to FAT32.

This format uses a 32-bit file allocation table, which greatly enhances its ability to manage disks and breaks through the limitation of 2gb per partition in fat 16. After using fat32 partition format, users can define a large hard disk as a partition without dividing it into several partitions, which greatly facilitates the management of the hard disk. Moreover, the biggest advantage of fat32 is that the capacity of each cluster in fat32 partition format is fixed at 4kb, and a partition does not exceed 8gb. Compared with fat 16, it can greatly reduce the waste of hard disk space and improve the utilization efficiency of hard disk.

At present, the operating systems supporting this disk partition format are win 97, win 98 and win 2000/XP. However, this partition format also has its disadvantages. First of all, due to the expansion of file allocation table, the disk partitioned in fat32 format is slower than the hard disk partitioned in fat 16 format. In addition, because dos system and some early application software don't support this partition format, the old dos operating system and some old application software can't be used after adopting this partition format.

3、ntfs

NTFS is the file system of Windows NT, and its biggest advantage is its good security and stability. NTFS with 32-bit kernel provides security settings for disk directories and files, and specifies access rights, so it is difficult to be attacked by viruses. NTFS can automatically record and change files, and has the ability to repair files without running disk tools such as disk defragmentation. The system is not easy to crash, and errors can be quickly fixed. Each cluster has only 5 12 bytes, and the hard disk utilization rate is the highest. Its main shortcomings are high barriers, behind closed doors, resulting in poor compatibility. NTFS of Windows NT can access the FAT file system, but the reverse access will be denied. For example, under DOS, the system will display "invalid drive specification". In Windows NT 4.0, the function of one-way conversion from FAT to NTFS is provided. In the latest Windows 2000 with NT kernel, the function of converting FAT to NTFS or FAFAT32 is provided. These transformations should be carefully considered before continuing.

The Ntfs partition format is not familiar to ordinary computer users. It is the hard disk partition format of the network operating system windows nt, and users who use windows nt must deal with this partition format. Its obvious advantages are excellent security and stability, and it is not easy to produce file fragments in use, which is beneficial to the space utilization of hard disk and the running speed of software. It can record the user's operation, and by strictly limiting the user's authority, each user can only operate according to the authority given by the system, which fully protects the security of the network system and data. However, there are not many operating systems that support this partition format at present. In addition to windows nt, win 2000 winxp win2003 also supports this hard disk partition format.

Linux file system classification: ext2: The upgraded version of ext3:ext2, the file system commonly used in early Linux, and the upgraded version of ext4:ext3 with logging function greatly changed the RAFMS: Memory file system, and the speed was very fast. Keywords network file system, sun invention, Mainly used for remote files * * * Enjoy MS-DOS: MS-DOS file system VFAT: file system FAT adopted by Windows 95/98 operating system: file system NTFS adopted by Windows XP operating system: file system HPFS adopted by Windows NT/XP operating system: OS/ 2 file system adopted by operating system PROC: virtual process file system Sun: file system adopted by most optical discs Sun: file system adopted by OS NCPFS: file system adopted by Novell server SMBFS: file system sharing SMBFS: advanced log file system developed by Sambasgi, supporting super-large files Sun: log file system adopted by IBM AIX Reiserfs: file system based on balanced tree structure, etc.

4. Virtual file system, all file systems supported by VFS * * linux are called logical file systems, and Linux adds an interface layer of VFS to the traditional logical file system. Virtual file system (VFS) is located at the top of the file system, which manages various logical file systems, shields the differences among various logical file systems, and provides a unified access interface for files and devices.

5. Logical structure of files The logical structure of files can be divided into two categories: byte stream unstructured files and record structured files. A file consisting of a byte stream (byte sequence) is an unstructured file or a stream file. It is simply regarded as a series of byte sequences, regardless of the internal logical structure of the file, which is convenient for adding content anywhere in the file. A file composed of records is called a record file. Record is the basic information unit of this file type, and record file is a common file in information management.

6. File type Ordinary file: usually stream file directory file: used to represent and manage all files in the system; Shared device files for files in different directories: including block device files and character device files. Block device files represent disk files, optical disks, etc. Character device files operate terminals, keyboards and other devices according to characters. FIFO file: a way to provide communication between processes. Socket file: This file type is related to network communication.

7. File structure: including index node and data index node: also called I node. In the file system structure, it contains the information records of the corresponding files, including file permissions, file names, file sizes, storage locations, establishment dates, etc. The inodes of all files in the file system are stored in the inode table. Data: the actual content of the file. It can be empty or large, with its own structure.

8.ext2 file system The data block size of ext2 file system is generally 1024B, and the inode:inode used in 2048B or 4096Bext2 file system adopts multiple index structure, which is mainly reflected in direct pointers and three indirect pointers. The direct pointer contains 12 direct pointer blocks, which directly point to the data block containing file data. The last three indirect pointers are designed to adapt to the change of file size.

Network model:

OSI seven-layer model

application layer

Presentation layer

Meeting layer

transport layer

Network layer

data link layer

physical layer

TCP/IP four-layer model

application layer

transport layer

IP layer

Network interface layer