This article is about file systems . When installing Windows, it prompts you to select the file system on the partition where it will be installed, and PC users must choose from two options FAT or NTFS.
In most cases, users are content knowing that NTFS is "better" and choose this option.
However, sometimes they wonder and what exactly is better?
In this article, I will try to explain what is a file system, what they are, how they differ, and which one should be used.
The article simplified some technical features file systems for a more understandable perception of the material.
File system is a way of organizing data on storage media. The file system determines where and how files will be written to the media and provides the operating system with access to those files.
Additional requirements are imposed on modern file systems: the ability to encrypt files, access control for files, and additional attributes. Usually the file system is written at the beginning of the hard disk. ().
From an OS point of view, HDD is a set of clusters.
cluster is an area of a disk of a certain size for storing data. The minimum cluster size is 512 bytes. Since the binary number system is used, the sizes of clusters are a multiple of a power of two.
The user can figuratively imagine a hard drive as a checkered notepad. One cell on the page is one cluster. The file system is the content of the notepad, and the file is the word.
For hard drives in PC in this moment The two most common file systems are: FAT or NTFS. First appeared FAT (FAT16), then FAT32, and then NTFS.
FAT(FAT16) – is an abbreviation for File Allocation Table(in translation File Allocation Table).
The FAT structure was developed by Bill Gates and Mark MacDonald in 1977. It was used as the main file system in DOS operating systems and Microsoft Windows(before Windows ME).
There are four versions of FAT - FAT12, FAT16, FAT32 and exFAT. They differ in the number of bits allocated to store the cluster number.
FAT12 mainly used for floppy disks, FAT16- for small disks, and the new exFAT mainly for flash drives. Maximum size cluster, which is supported in FAT, is 64Kb. ()
FAT16 first introduced in November 1987. Index 16 in the name indicates that 16 bits are used for the cluster number. As a result, the maximum size of a disk partition (volume) that this system can support is 4GB.
Later, with the development of technology and the advent of disks with a capacity of more than 4 GB, a file system appeared. FAT32. It uses 32-bit cluster addressing and was introduced with Windows 95 OSR2 in August 1996. FAT32 limited in volume size to 128GB. Also this system can support long filenames. ().
NTFS(abbreviation NewtechnologyFileSystem - New Technology File System) is the standard file system for the Microsoft Windows NT family of operating systems.
Introduced July 27, 1993 with Windows NT 3.1. NTFS is based on the HPFS file system (abbreviation highPerformanceFileSystem - High Performance File System), which was created by Microsoft together with IBM for the OS / 2 operating system.
Main features of NTFS: built-in capabilities to restrict access to data for various users and user groups, as well as assign quotas (restrictions on maximum volume disk space occupied by certain users), the use of a journaling system to improve the reliability of the file system.
The file system specifications are closed. Usually the cluster size is 4Kb. In practice, it is not recommended to create volumes larger than 2TB. Hard drives have just reached such sizes, perhaps in the future we will have a new file system. ().
During the installation of Windows XP, it is prompted to format the disk in the system FAT or NTFS. This means FAT32.
All file systems are built on the principle: one cluster - one file. Those. one cluster stores the data of only one file.
The main difference for the average user between these systems is the size of the cluster. “A long time ago, when disks were small and files were very small,” it was very noticeable.
Consider the example of one volume on a 120GB disk and a 10Kb file.
For FAT32 the cluster size will be 32Kb, and for NTFS- 4Kb.
AT FAT32 such a file will occupy 1 cluster, leaving 32-10=22Kb of unallocated space.
AT NTFS such a file will take up 3 clusters, leaving 12-10=2Kb of unallocated space.
By analogy with a notebook, a cluster is a cell. And having put a dot in a cell, we already logically occupy it all, but in reality there is a lot of free space.
Thus, the transition from FAT32 to NTFS allows you to make better use of your hard drive, if available a large number small files in the system.
In 2003, I had a 120GB drive divided into 40 and 80GB volumes. When I switched from Windows 98 to Windows XP and converted the drive from FAT32 in NTFS, I got about 1GB of free disk space. At that time it was a significant "increase".
To find out which file system is being used on hard volumes disk of your PC, you need to open the volume properties window and on the tab "General" read this data.
Volume- this is a synonym for a disk partition, users usually call the volume “drive C”, “drive D”, etc. An example is shown in the picture below:
AT currently disks of 320 GB and more are widely used. Therefore, I recommend using the system NTFS for optimal use disk space.
Also, if there are several users on the PC, NTFS allows you to configure file access in such a way that different users could not read or modify files of other users.
In organizations when working in local network system administrators use other features of NTFS.
If you are interested in organizing access to files for several users on one PC, then the following articles will describe this in detail.
When writing the article, materials from the sites en.wikipedia.org were used
Article author: Maxim Telpari
PC user with 15 years of experience. Video Course Support Specialist Confident User PC", having studied which you will learn how to assemble a computer, install Windows XP and drivers, restore the system, work in programs and much more.
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Many users are faced with a misunderstanding of the basics of how Windows file systems work. It would seem, why an unnecessary theory? In fact, it is the knowledge of the deep functioning of various file systems that allows you to correctly choose one or another file system for one or another storage medium. Sometimes an error in the choice can become critical later when solving the problem of information recovery or premature wear of the media.
The file system consists of a file management system and a collection of files on a certain type of media (CD, DVD, FDD, HDD, Flash, etc.). A file management system provides users and applications with the ability to access files, store them, and maintain the integrity of their content. The most common long-term storage medium in modern computing systems is a hard drive - "Winchester". This term applies to any sealed disc with aerodynamically designed magnetic read heads.
The file systems of modern operating systems are installed on hard disk partitions.
FAT 32. Simplicity and reliability.
There are three FAT file systems: FAT12 (for FDD floppy disks), FAT16, FAT32. They differ in the number of bits (12, 16, 32) to indicate the cluster number in the file management system. In FAT file systems, the logical disk space of any logical drive is divided into system area and data area. BR- boot record boot record; RS - reserved sectors; FAT1, FAT2 - tables 1 and 2 of file allocation; RDir (Root directory, ROOT) – root directory. The data area is divided into clusters, which are 1 or more contiguous sectors. In the FAT table, clusters belonging to the same file are linked in a chain. The map of the data area is, in fact, the File Allocation Table (FAT) Each element of the FAT table (12, 16 or 32 bits) corresponds to one disk cluster and characterizes its state: free, busy or is a bad cluster (bad cluster) . The FAT16 file management system uses a 16-bit word to indicate the cluster number, and 65536 clusters can be addressed.
A cluster is the minimum addressable unit of disk space allocated for a file. A file or directory occupies an integer number of clusters. Splitting a data area into clusters instead of using sectors allows you to: reduce the size of the FAT table, reduce file fragmentation, reduce the length of file chains, speed up file access. The last cluster may not be fully utilized, resulting in a noticeable loss of disk space when big size cluster. On a floppy disk, a cluster occupies 1 or 2 sectors. On the hard disk - 4, 8, 16, 32, 64 - sectors in one cluster. Each element has the following structure: file name, file attribute, backing field, creation time, creation date, date last access, reserve, date of last modification, time of last modification, initial Fat cluster number, file size.
AT this example the file named MyFile.txt is located starting from the 8th cluster and occupies 12 clusters. The chain of clusters for this case: 8,9,A,B,15,16,17,19,1A,1B,1C,1D. Cluster number 18 is marked as bad by code F7. It cannot be used to host data. This code is set by the disk formatting and checking utilities. Cluster 1D is marked with the FF code as the final, belonging given file. Free clusters are marked with code 0. When a new cluster is allocated for writing to a file, the 1st free cluster is taken. As files on the disk are changed, deleted, moved, enlarged, and reduced, this rule placement leads to fragmentation, i.e. the data of one file is not located in adjacent clusters, and sometimes very remote friend from friend. A complex chain is formed. This results in slower file handling. Since Fat is used very intensively when accessing the disk, it is loaded into RAM. The Fat32 system is much more efficient in using disk space, as it uses clusters smaller compared with previous versions fat. Compared to Fat16, this gives a savings of 10-16%.
A directory element in an attribute field can store the following values:
1) archive (installed when the file is changed and removed by the program that executes backup files to other media)
2) directory;
3) volume label;
4) systemic;
5) hidden;
6) read-only.
Long names in FAT32 are enforced using multiple directory entry entries: for a single file (one entry is one entry for the 8.3 name, and 24 entries for the longest name, which can be up to 256 characters long. Therefore, long names are not recommended.
The main disadvantage of FAT is slow work with files. When creating a file, the rule works - the first free cluster is selected. This leads to disk fragmentation and complex file chains. Hence the slowdown in working with files.
Basically, file FAT system is something to be avoided today. Therefore, it is vital to choose the right one that will allow you to avoid this file system.
NTFS: convenience and high speed.
One of the basic concepts used when working with NTFS is the concept of a volume. It is possible to create a fault-tolerant volume that occupies several partitions, that is, the use of RAID technology. NTFS divides the entire usable disk space of a volume into clusters - blocks of data addressed as units of data. NTFS supports cluster sizes from 512 bytes to 64 KB; 2 or 4 KB of the disk are allocated for the MFT zone - the space that can be occupied by the main MFT service metafile, increasing in size. Writing data to this area is not possible. The MFT zone is empty so that the service file (MFT) does not fragment as much as possible as it grows.
MFT (general file table) - a centralized directory of all other disk files, including itself. MFT is divided into records fixed size in 1 KB, each entry corresponds to a file. The first 16 files are of a service nature and are inaccessible to the operating system - they are called metafiles, and the very first metafile is the MFT itself. These first 16 MFT elements are the only part of the disk that has a strictly fixed position. A copy of these same 16 entries is kept in the middle of the volume for security, as they are very important. The remaining parts of the MFT file can be located in arbitrary places on the disk - you can restore its position using itself, "hooking" on the very basis - on the first element of the MFT. Each file in NTFS is represented by streams, it has no data, but "streams". One of the streams is the file data. You can define multiple data streams for a single file.
Main features of NTFS:
Work on large disks is efficient (much more efficient than in FAT);
There are means to restrict access to files and directories;
NTFS partitions provide local security both files and directories;
A transaction mechanism has been introduced, in which file operations are logged;
Significant increase in reliability;
Removed many restrictions on the maximum number disk sectors and/or clusters;
A file name in NTFS, unlike the FAT and HPFS file systems, can contain any characters, including the full set of national alphabets, since the data is presented in Unicode, a 16-bit representation that gives 65535 different characters. Maximum length file name in NTFS - 255 characters.
NTFS also has built-in compression that can be applied to individual files, entire directories, and even volumes (and subsequently revoke or assign them as you see fit). A directory on NTFS is special file A that stores links to other files and directories.
NTFS provides file-level security; this means that permissions to volumes, directories and files may depend on account user and the groups to which he belongs. Each time a user accesses a file system object, their permissions are checked against a list of permissions. this object. If the user has a sufficient level of rights, his request is granted; otherwise, the request is rejected. This security model applies to both local user login on NT machines and remote network requests.
NTFS also has some self-healing features. NTFS supports various mechanisms for checking system integrity, including transaction logging, which allows you to replay file write operations against a special system log.
The main drawback of the NTFS file system is that service data takes up a lot of space (for example, each element of the directory takes 2 KB) - for small partitions, service data can take up to 25% of the media volume.
Thus, when choosing a file system type, we do not choose some abstract action, we make a set of decisions that affect the entire system as a whole. Why do you need to know all the ins and outs of the file system in such detail? It is necessary for her possible recovery, which we will cover in one of the following articles =)
Windows supports several file systems for various external devices:- NTFS is the main file system Windows families NT;
- FAT (File Allocation Table) is a simple file system used by Windows for flash storage devices, as well as for compatibility with other operating systems when installed on disks with multiple boot. The main element of this file system is the FAT file allocation table (after which the entire file system is named), which is necessary to determine the location of the file on the disk. There are three versions of FAT, which differ in the bitness of identifiers indicating the location of files: FAT12, FAT16 and FAT32;
- exFAT (Extended FAT - extended FAT) is a development of the FAT file system using 64-bit identifiers. Mainly used for flash memory devices;
- CDFS (CD-ROM File System) is a file system for CDs that combines ISO 9660 1 formats. ISO 9660 - ISO (International Organization for Standardization) standard for CD file systems and Joliet 2 Joliet is an extension of the ISO 9660 standard developed by Microsoft. Removes hard restrictions on file naming ;
- UDF (Universal Disk Format) universal format disks) - file system for CD and DVD discs, designed to replace ISO 9660.
For further presentation, you need to know the following important concepts: disk, partition, simple and composite volumes, sector, cluster .
Disk ( disk ) - device external memory , such as a hard drive or an optical disc (CD, DVD, Blu ray).
A partition is a contiguous part of a hard drive. A disk can contain multiple partitions.
Volume ( volume ) or logical disk ( logical disk ) - an area of external memory with which operating system works as one. Volumes are simple and composite.
Simple volume (simple volume) - a volume consisting of one partition.
Composite volume (multipartition volume) - a volume consisting of several partitions (optionally on the same disk).
The concepts of a partition and a simple volume are different: firstly, partitions are formed, basically, only on hard drives, and volumes are also created on other external storage devices (for example, on optical discs and flash memory devices), secondly, the concept of "partition" is associated with physical device, and the concept of "volume" - with logical representation external memory.
Sector ( sector ) – fixed size data block on disk; the smallest unit of information for a disk. The typical sector size for hard drives is 512 bytes, for optical drives it is 2048 bytes. The division of the disk into sectors occurs once during the creation of the disk in the process. low-level formatting and usually cannot be changed.
A cluster ( cluster ) is a logical block of data on a disk that includes one or more sectors. The number of sectors that make up a cluster is usually a multiple of powers of two. The cluster size is set by the operating system through a high-level formatting process that can be performed multiple times.
When written to disk, a file will always occupy an integer number of clusters. For example, a 100 byte file on a file system with a 4 KB cluster size will take up exactly 4 KB.
The choice of the cluster size is connected with the following considerations. Small clusters reduce the amount of wasted disk space created by placing a file across an integer number of clusters. But at the same time, the total number of clusters on the disk increases and the size of the file system service structures that store information about files increases.
Features of NTFS
File system NTFS (New Technology File System) was developed by Microsoft in the early 1990s. as the main file system for server versions of Windows operating systems. NTFS was introduced in 1993 with the Windows NT 3.1 operating system.
NTFS is currently regarded as the file system of choice for both server and client versions of Windows.
NTFS uses 64-bit cluster identifiers, so theoretically an NTFS volume can contain 264 clusters (16 EB 3 2 10 bytes = 1 kilobyte (KB), 2 20 bytes = 1 megabyte (MB), 2 30 bytes = 1 gigabyte (GB), 2 40 bytes = 1 terabyte (TB), 2 50 bytes = 1 petabyte (PB), 260 bytes = 1 exabyte (EB), 270 bytes = 1 zettabyte (ZB).). However, current implementations in Windows only support 32-bit cluster addressing, which, with a maximum cluster size of 64 KB (216 bytes), allows an NTFS volume to reach a size of up to 256 TB:
2 32 * 2 16 bytes = 2 48 bytes = 2 8 * 2 40 bytes = 256TB.
For volumes larger than 4 GB, when Windows formatting suggests a default cluster size of 4 KB.
Let's list some features of NTFS [ , page 761]:
- recoverability - the ability of a file system to revert to working condition after the failure occurs. This possibility is realized, firstly, due to the support of atomic transactions, and secondly, due to the redundancy of information storage. An atomic transaction is an operation on the file system that results in a change to it, which is either completely successful or not performed at all (i.e., in case of failure during an atomic transaction, all changes are rolled back). Redundancy is used when storing the most important file system data that is critical for its correct operation;
- security (security) - protection of files from unauthorized access. Implemented with a model Windows Security, discussed in Lecture 9 "Security in Windows";
- encryption (encryption) - converting a file into an encrypted code that cannot be read without a key. Conventional security mechanisms, such as assigning file permissions to users, do not full protection information, for example, if you move the disc to another computer. The operating system administrator can always access other users' files, even on an NTFS volume. Therefore, NTFS includes support for the Encrypting File System (EFS), which makes it easy to encrypt and decrypt files;
- support for RAID (Redundant Array of Inexpensive (Independent) Disks - an array of inexpensive (independent) disks with redundancy) - the ability to use multiple disks to store information; data from one disk is automatically copied to others, thereby providing increased reliability;
- disk quotas for users (Per-User Volume Quotas) - the ability to allocate a certain disk space for each user (quotas); NTFS does not allow the user to write data to the disk beyond the allocated quota.
Structure of NTFS
The structure of an NTFS volume is shown in Figure 17.1.
Rice. 17.1.
At the beginning of the volume there is a volume boot record ( Volume Boot Record ), which contains the code Windows boot, volume information (in particular, file system type), addresses system files($ Mft and $MftMirr - see below). The boot record usually takes 8 KB (16 first sectors).
In a certain area of the volume (the address of the beginning of this area is indicated in the boot record), the main NTFS system structure is located - the main file table ( Master file Table , MFT ). The entries in this table contain all information about the location of files on the volume, and small files are stored directly in the MFT entries.
important NTFS feature is that all information, both user and system, is stored as files. System file names begin with the "$" sign. For example, a volume's boot entry is in the $ Boot file, and the master file table is in the $ Mft file. This organization of information allows you to work uniformly with both user and system data on the volume.
Since the MFT is the most important system structure, which is most often accessed during operations with the volume, it is beneficial to store the $ Mft file in a contiguous area of the logical disk in order to avoid its fragmentation (placement in different areas of the disk), and, therefore, increase the speed of working with it. For this purpose, when formatting a volume, a contiguous area is allocated, called a zone.
NTFS (English) New Technology File System- "file system new technology”) is a standard file system designed for the OS family Microsoft Windows NT.
NTFS came to replace the FAT file systems previously used in Microsoft Windows and MS-DOS. NTFS maintains a metadata system, and also uses specialized data structures to store information about files, which can improve performance, reliability, and disk space efficiency. NTFS has built-in features that allow you to restrict access to data for different groups users and individual users (ACLs - access control lists), assign quotas (restrictions on the maximum amount of disk space occupied by a particular user). To improve reliability, NTFS uses a journaling system.
The NTFS file system was developed based on the HPFS (High Performance File System) system, which was created jointly by IBM and Microsoft for the OS / 2 operating system. However, with the acquisition of very useful innovations, such as journaling, quoting, auditing, and access control, NTFS has lost the high performance of file operations inherent in HPFS. At the time of its inception, NTFS included all the latest technological advances, such as:
Ability to work with large discs. The NTFS cluster size is 512 bytes, but it can vary up to 64K. Much more important quality NTFS is the theoretical ability to work with volumes of 16,777,216 terabytes. Theoretical only because such hard drives have not yet been created.
Sustainability. NTFS contains two copies of the FAT analogue, called the MFT (Master File Table). MFT differs from FAT MSDOS in that it more closely resembles a database table. In case of damage to the original MFT due to a hardware error (for example, the appearance of a bad sector), when next boot the system uses a copy of the MFT, automatically creating new original taking into account all damage. But this is not the main advantage. The main thing is that when writing files to NTFS drive uses a transaction system. This system came from the DBMS, where data integrity protection is given Special attention which can already say a lot about its effectiveness. This system provides absolute data safety when copying, moving and deleting files or directories. If changes are made to the file, the changes that were in the controller's cache in or memory at the time of the crash and were not written to disk will be lost.
Security. NTFS treats files as objects. And each file object has its own properties such as creation date, name, archive status, security descriptor and date. latest update. The file object also contains a set of methods that allow you to work with it, such as write, read, close and open. Users, including network users, call these methods to access the file, and the Security Reference Monitor determines whether the user has the rights necessary to call one of these methods. In addition, files can be encrypted, but this should be done carefully. If you reinstall the system, you will not be able to read encrypted files without ERD.
Data compression. Unlike DriveSpace, in which disks could only be compressed as a whole, NTFS allows you to compress individual files and directories. This allows you to save disk space, for example, "on the fly" to compress text files or large graphic files BMP format, and all this will be transparent to the user.
Support ISO format Unicode. Unlike the format ASCII, which used 7 or 8bit to encode each character, Unicode uses 16bit. This will allow a normal user to name files in absolutely any language, and the system will support this, without the requirement to change the code page, as W9x did and DOS.
There are several versions of NTFS. Windows NT 4.0 and Windows NT 3.51 use v1.2, Windows 2000 ships with v3.0, with Windows Server 2003 and Windows XP - v3.1. Some latest versions are designated v4.0, v5.0, that is, in full accordance with the versions of Windows NT with which they are shipped.
Windows NT has NTFS 4.0 file system, Windows 2000/XP has NTFS 5. When you connect a 2000/XP disk with NTFS 4.0, it is automatically converted by the operating system to NTFS 5.0.
The file system specifications are closed. This presents some difficulty for it to be supported by third party products that are not owned by Microsoft. For example, developers of drivers for free operating systems are forced to reverse-engineer the system.
There are many ways to store information and programs on a hard drive. A very well-known system that saves various information in the form of files, grouping them into folders with a unique assignment. However, few people thought about how the physical storage of information on the media actually takes place.
In order to physical media information could be stored, it needs to be prepared for use in a computer operating system. The operating system allocates free disk space to save information. To do this, you need to divide the disk into small containers - sectors. Formatting a disk at a low level allocates a certain size for each sector. The operating system groups these sectors into clusters. Top-level formatting sets all clusters to the same size, typically between 2 and 16 sectors. In the future, one or more clusters are allocated for each file. The cluster size depends on the operating system, disk capacity, and the required speed.
In addition to the area for storing files on the disk, there are areas necessary for the operation of the operating system. These areas are for storing boot information and information for matching file addresses to physical position on disk. The boot area is used to start the operating system. After BIOS boot the boot area of the disk is read and executed to start the operating system.
FAT file system
The FAT file system appeared along with the operating system. Microsoft system DOS, after which it was improved several times. It has FAT12, FAT16 and FAT32 versions. The name FAT itself comes from the file system's use of a kind of database in the form of a "file allocation table" (File Allocation Table), which contains an entry for each cluster on the disk. The version numbers refer to the number of bits used in the item numbers in the table. Therefore, the file system has a limit on the supported disk size. In 1987, it did not support disks larger than 32 MB. With advent of Windows 95 came out a new version FAT32 file system with theoretical support for drives up to 2 TB. Constant problems with supporting large disks appear due to the fixed number of elements, limited number bits used in determining the position of the cluster. For example, the FAT16 version does not support more than 2 16 or 65536 clusters. The number of sectors in a cluster is also limited.
Another problem with large disks was the inability to use huge space dedicated to small files. Due to the fact that the number of clusters is limited, their size was increased in order to cover the entire capacity of the disk. This leads to inefficient use of space when storing most files that are not a multiple of the cluster size. For example, FAT32 allocates 16 KB clusters for disk partitions ranging from 16 GB to 32 GB. To store a 20 KB file, you will need two 16 KB clusters, which will occupy 32 KB on disk. 1 KB files take up 16 KB of disk space. Thus, on average, 30-40% of the disk capacity is wasted for storing small files. Partitioning a disk into small partitions allows you to reduce the size of the cluster, but it is not used in practice for disks with a capacity of more than 200 GB.
File fragmentation is also not small problem file system. Since a file may require several clusters to locate, which may not be physically consecutive, the time it takes to read slows down programs. Therefore, there is a constant need for.
NTFS file system
In the early 1990s, Microsoft began developing completely new software designed for environments with more resource consumption than typical home users. For the needs of business and industry, the resources provided by DOS-based Windows operating systems have become insufficient. Microsoft Corporation worked with IBM on the OS / 2 operating system with the HPFS (High Performance File System) file system. Corporate development did not bring success and soon each company again went its own way. Microsoft has developed various versions Windows NT operating system, on which Windows 2000 and Windows XP are built. Each of them uses own version NTFS file system, which continues to evolve.
NTFS (New Technology File System) is the standard file system for operating systems based on Windows based NT. It was designed to replace FAT. NTFS is more flexible than FAT. Its system areas store mostly files rather than fixed structures like FAT, allowing them to be modified, expanded, or moved during use. A simple example is the Master File Table (MFT) - "master file table". MFT is a kind of database with various information about files on disk. Small files (1 KB or less) can be stored directly in the MFT. For big NTFS files allocates clusters, but unlike FAT, the cluster size usually does not exceed 4 KB, and the built-in compression method eliminates problems with unused space allocated for files. And in NTFS you can use .
The NTFS file system is designed for a multi-user environment and has built-in security and access control mechanisms. For example, OS Windows 2000 and Windows XP (except "Home Edition") allow you to set access permissions for individual files and encrypt them. However, the high level of security complicates the work ordinary users with a computer. You must be extremely careful when setting passwords and file permissions so as not to lose important data.
