What does ntfs file system mean? Comparison of file systems

Many users are faced with a lack of understanding of the basics of operation file systems Windows. It would seem, why an unnecessary theory? In fact, it is knowledge of the deep functioning of various file systems that allows you to correctly select one or another file system for a particular storage medium. Sometimes an error in 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 specific type of media (CD, DVD, FDD, HDD, Flash, etc.). A file management system enables users and applications to access files, save them, and maintain the integrity of their contents. The most common long-term storage medium in modern computing systems is the hard drive – “Winchester”. This term applies to any sealed disk with aerodynamically designed magnetic read heads.

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 floppy disks FDD), 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 – file allocation tables 1 and 2; RDir (Root directory, ROOT) – root directory. The data area is divided into clusters, which represent 1 or more adjacent sectors. In a 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 a bad cluster. . To indicate the cluster number in the FAT16 file management system, a 16-bit word is used, and 65536 clusters can be addressed.

A cluster is a minimally addressable unit disk memory, allocated for the file. A file or directory occupies an integer number of clusters. Dividing the 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 used, which will lead to a noticeable loss disk space with a large cluster size. On a floppy disk, the cluster occupies 1 or 2 sectors. The hard drive has 4, 8, 16, 32, 64 sectors in one cluster. Each element has the following structure: file name, file attribute, reserve field, creation time, creation date, date last access, reserve, last modification date, last modification time, initial Fat cluster number, file size.

In this example, a file named MyFile.txt is placed starting from the 8th cluster and occupies 12 clusters. Cluster chain for this case: 8,9,A,B,15,16,17,19,1A,1B,1C,1D. Cluster number 18 is marked with code F7 as bad. It cannot be used to host data. This code is set by disk formatting and checking utilities. Cluster 1D is marked with the FF code as the final one belonging to this file. Free clusters are marked with code 0. When a new cluster is allocated, the first free cluster is taken for writing to a file. As files on the disk are changed, deleted, moved, grown and shrunk, this placement rule leads to fragmentation, i.e. the data of one file is not located in adjacent clusters, but sometimes very distant from each other. A complex chain is formed. This leads to slower work with files. Since Fat is used very intensively during disk access, it is loaded into RAM. The Fat32 system uses disk space much more efficiently because it uses smaller clusters compared to previous versions Fat. Compared to Fat16, this gives a savings of 10-16%.

A directory item's attribute field can store the following values:

1) archive (installed when a file is changed and removed by a program that backs up files to another medium);

2) directory;

3) volume label;

4) systemic;

5) hidden;

6) read-only.

Long names in FAT32 are provided by using multiple directory entry entries: for one 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. Therefore, long names are not recommended.

The main disadvantage of FAT is slow work with files. When creating a file, the rule is that the first free cluster is allocated. This leads to disk fragmentation and complex file chains. This results in slower work with files.

Basically, the FAT file system is something to be avoided today. Therefore, it is vital to choose a suitable one that will allow you to avoid this file system.

NTFS: convenience and high speed.

One of the main concepts used when working with NTFS is the concept of volume. It is possible to create a fault-tolerant volume that occupies several partitions, that is, use RAID technology. NTFS divides all of the usable disk space on a volume into clusters—blocks of data that are addressed as data units. NTFS supports cluster sizes from 512 bytes to 64 KB; 2 or 4 KB of disk are allocated for the MFT zone - space that can be occupied by the main service metafile MFT, increasing in size. It is not possible to write data to this area. The MFT zone is empty so that the service file (MFT) does not become fragmented as it grows.

MFT (common file table) is a centralized directory of all other files on the disk, including itself. MFT is divided into fixed size records of 1 KB, each record corresponding to a file. The first 16 files are of a service nature and are inaccessible to the operating system - they are called metafiles, with the very first metafile being 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 safety 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 the file itself, “catching” on the very basis - on the first MFT element. Each file in NTFS is represented using streams; it does not have data, but rather "streams". One of the streams is file data. You can define multiple data streams for one file.

Main features of NTFS:

Work on large disks occurs efficiently (much more efficiently than in FAT);

There are tools to restrict access to files and directories;

NTFS partitions provide local security for both files and directories;

A transaction mechanism has been introduced that provides logging file operations;

Significant increase in reliability;

Many restrictions on the maximum number of disk sectors and/or clusters have been removed;

Filename in NTFS, as opposed to filename FAT systems and HPFS, can contain any characters, including the full set of national alphabets, since the data is represented in Unicode - a 16-bit representation that gives 65535 different characters. The maximum length of a file name in NTFS is 255 characters.

NTFS also has built-in compression capabilities that you can apply to individual files, entire directories, and even volumes (and then undo or reassign them as you see fit). A directory in NTFS is special file, which stores links to other files and directories.

NTFS provides file-level security; this means that access rights to volumes, directories and files may depend on account user and the groups to which he belongs. Every time a user accesses a file system object, his access rights are checked against the permission list of this object. If the user has sufficient rights, his request is granted; otherwise the request is rejected. This security model applies to both local user registration on NT computers and remote network requests.

The NTFS system also has certain self-healing capabilities. NTFS supports various mechanisms for verifying system integrity, including transaction logging, which allows file write operations to be replayed against a special system log.

The main disadvantage of the NTFS file system is that service data takes up a lot of space (for example, each directory element takes up 2 KB) - for small partitions, service data can take up to 25% of the media volume.

Thus, when choosing a file system type, we are not choosing some abstract action, we are making a set of decisions that affect the entire system as a whole. Why know all the ins and outs of the file system in such detail? This is necessary for her possible restoration, which we will talk about in one of the following articles =)

At Windows installation XP you will be prompted to format existing section, on which the OS is installed, into the NTFS file system. You need to figure out what it is.

NTFS is the only file system in Windows that allows you to assign access rights to various files. By setting users specific permissions on files and directories, the user can protect sensitive information from unauthorized access.

The main purposes of NTFS are:

• ensuring high-speed execution of standard operations on files, such as reading, writing, searching
• ensuring provision additional features, including recovering damaged file systems on extremely large drives.

NTFS began being used with Windows NT 3.1 in 1993. Here are its main technological achievements:

1. Work with big disks. NTFS has a cluster size of 512 bytes, but it can be changed up to 64K.
2. Sustainability. NTFS contains two copies of the FAT analogue, which are called MFT (Master File Table). If the original MFT is damaged in the event of a hardware error, then the next time the system boots, it uses a copy of the MFT, and automatically creates a new original, taking into account the damage. NTFS uses a write transaction system files to disk.
3. Security. NTFS treats files as objects. Every file object has properties such as its name, creation date, date last update, archival status. The file object also contains a set of methods that allow you to work with it, such as open, close, read and write.
4. Data compression. NTFS allows you to compress individual directories and files. This allows you to save disk space, for example you can compress large graphic files BMP format, or text files.
5. Support ISO format Unicode. The Unicode format uses 16bit to encode each character. A simple user can name files in any language - the system will support this without requiring you to change the code page, as DOS and W9x did.

Basic properties of the NTFS file system:

1. NTFS has security characteristics, allows you to control access to data and owner privileges to ensure the integrity of important data. NTFS folders and files can have access rights assigned to them.
2. NTFS has the ability to introduce quotas. This property is usually necessary system administrators, large companies where they work a large number of users who do not keep information up to date and who store unnecessary files, thereby taking up disk space. Since the administrator cannot monitor all this, he can impose a disk usage quota on a specific user. If the user exceeds the quota assigned to him, a corresponding entry will be made in the event log. To enable disk quotas:

• so that the disk is in NTFS format
• in the properties of the Tools-Folder Options-View folder, uncheck the Simple File Sharing checkbox.
• In the Quota tab that appears, you need to check the box for Enable quota managment. This will set a soft quota, which will issue a warning that the user has exceeded the quota, but he will have the right to write. To deny access to this volume to a user if the quota is exceeded, you must select the Deny disk space to users exceeding quota limit check box.

File system NTFS (New Technologies File System- file system new technology) was released along with the OS Windows NT 3.5 in 1993 Before Windows release 2000 development of the two OS lines was separate, and consumer OS Windows 95/98/Me were limited to use FAT16 or FAT32. In contrast, the ruler NT, including Windows XP, supports all systems (except Windows NT4, not familiar with FAT32).

System NTFS contains many improvements over systems FAT. The most important ones relate to:

· optimized use of space on large volumes,

· correcting errors after accidents,

· data protection from unauthorized access,

indexing service

· compression and data encryption,

· restoring the system after serious failures.

NTFS can manage partitions of several hundred terabytes in size. As for security, administrators were able to use built-in security functions: user access policies for files and folders, file encryption systems EFS (Encryption File System– encrypted file system).

System NTFS, used in versions of Windows up to Windows 2000, did not meet modern requirements, in particular:

· limited the number of volumes to 26 (disks A to Z);

· changing a partition always required a reboot;

· information about NTFS volumes was stored in the registry, which made it difficult to use the disk with another system.

These problems were solved in Windows 2000 by using LDM(Logical Disk Manager – logical disk manager), which no longer requires assigning drive letters. Improvements NTFS, used in Windows XP, were associated with:

· improvement bandwidth data,

· introducing the ability to set cluster size values ​​other than the fixed one of 512 bytes;

· improved administrative functions: indexing folders and limiting unexpected memory consumption.

File system NTFS represents an outstanding achievement of structuring: every element of the system is a file - even service information. Most main file V NTFS called MFT (Master File Table– general file table). Unlike FAT, which stores tables separately, at the beginning of the volume, NTFS places MFT in hidden files.

Chapter NTFS can be almost any size. Its maximum size is limited only by the size hard drives.

NTFS divides all useful storage space into clusters - data blocks, and the cluster size varies from 512 bytes to 64 KB (a 4 KB cluster is considered the standard).

Disk NTFS conditionally divided into two parts. The first 12% of the disk is dedicated to MFT zone- the space into which the metafile grows MFT. It is not possible to write any data to this area. The MFT zone is always kept empty - this is done so that the most important service file ( MFT) did not fragment during its growth. The remaining 88% of the disk is regular file storage space (Figure 9).

Rice. 9. Physical structure of NTFS

The mechanism for using the MFT zone is as follows: when files can no longer be written to regular space, the MFT zone is simply reduced (in current versions OS exactly twice), thus freeing up space for writing files. When space is freed up in the normal area, the MFT area may expand again. However, it is possible that ordinary files will remain in this zone.

MFT is located in the MFT zone and represents centralized directory of all other disk files(including yourself). MFT manages all volume files and so-called metadata by using relational base data. Information about files is placed in rows, and file attributes (hidden, encrypted, compressed, system, etc.) are written in columns.

MFT divided into fixed size records(usually 1 KB), and each entry corresponds to a file. The first 16 files are of a service nature and are not accessible to the OS - they are called metafiles, and the very first metafile is itself MFT. Files up to 900 bytes in size can fit entirely into one entry. For larger files MFT contains pointers to their location in disk memory. The same applies to folders: if they are small enough, they are completely included in MFT.

First 16 elements MFT- the only part of the disk that has a fixed position. The second copy of the first three records, for reliability (they are very important), is stored exactly in the middle of the disk. The rest of the MFT file can be located, like any other file, in arbitrary places on the disk - you can restore its position using the file itself, “catching” on the very basis - on the first element MFT.

Each metafile is responsible for some aspect of the system's operation. The advantage of this approach is flexibility. For example, in the file system FAT physical damage in the area itself FAT fatal for the functioning of the entire disk, and NTFS can shift, even fragment across the disk, all of its service areas, bypassing any surface faults - except for the first 16 elements MFT.

Metafiles are in root directory NTFS drive – they begin with the name symbol “$”. The following metafiles are currently used:

· $MFT– MFT itself;

· $MFTmirr– a copy of the first 16 MFT records, located in the middle of the disk;

· $LogFile– logging support file;

· $Volume– service information (volume label, file system version, etc.);

· $AttrDef– a list of standard attributes of files on the volume;

· $. - root directory;

· $Bitmap– volume free space map;

· $Boot – boot sector(if the partition is bootable);

· $Quota- a file that records user rights to use disk space;

· $Upcase– file-table of correspondence between capitals and capital letters in file names on the current volume.

All files located on the disk are mentioned in MFT. All information about the file (except for the data itself) is stored in this place: file name, size, disk location of individual fragments, etc. If one entry is missing for information MFT, then several are used, and not necessarily in a row.

Files small size(up to 900 bytes) are stored directly in MFT, in the space remaining from the main data within one record MFT. Files that occupy hundreds of bytes usually do not have their “physical” embodiment in the main file area - all the data of such a file is stored in one place - in MFT.

The file name can contain any characters, including the full set of national alphabets, since the data is presented in Unicode– 16-bit representation, which gives 65535 different characters. The maximum file name length is 255 characters.

Catalog at NTFS is a specific file that stores links to other files and directories, creating a hierarchical structure of data on disk. The catalog file is divided into blocks, each of which contains the file name, basic attributes and a link to the element MFT, which already provides full information about a directory item. The internal directory structure is binary tree (B-tree). What this means is that to find a file with a given name in a linear directory, such as FAT, the OS has to look through all the entries in the directory until it finds the one it needs. A binary tree arranges file names in such a way that searching for a file takes more time. in a fast way– by obtaining two-digit answers to questions about the file location. The question that a binary tree can answer is: in which group, relatively of this element, is the name you are looking for – above or below? Such a search begins with a question to the middle element, and each answer narrows the search area by an average of two times. The files are sorted alphabetically, and the answer to the question is carried out in the obvious way - by comparing the initial letters. The search area, narrowed by half, begins to be explored in a similar way, starting again from the middle element. An example of B-tree search is shown in Fig. 10.

Thus, to search for one file among, for example, 1000, FAT an average of 500 comparisons will have to be made (it is most likely that the file will be found halfway through the search), while a B-tree based system will only have to make about 10 (2 10 = 1024).

The main directory of the disk - the root - is no different from ordinary directories, except for a special link to it from the beginning of the metafile MFT.

NTFS– a fault-tolerant system that can restore itself to the correct state in the event of almost any real failures.

In table 4 shows the restrictions imposed on file systems NTFS And FAT.

Table 4. File system limitations

For new OS Vista Microsoft company develops a new file system Windows Future Storage (WinFS – « upcoming storage system"), designed to replace NTFS And FAT. At the core WinFS lies modified NTFS with improved administration functions, organizing access to files, synchronizing and protecting file resources.

The new file system is designed to store files based on criteria for their content, i.e. author, content, name, source and last accessed user. Folder structure displayed in Conductor, is simply a virtual card.

The essence WinFS is the so-called data model- a mechanism that constantly administers and structures digital elements or "items" ( items). Items use descriptive elements that go beyond the concept of a file. These descriptive elements are not present in the file, but are entirely owned and controlled by WinFS. With this scheme, you can register not only files as objects, but also, for example, contacts, Internet links, letters, etc.

From the users' point of view, items remove the need to use a physical file location. Instead, the OS organizes data, depending on its content, into virtual folders. When searching for data, custom criteria like " All documents on the ICT course for the last two years» replace information about file format, authors, and location.

Microsoft implemented a changing item model in WinFS, i.e. users can define items themselves using metadata XML and indicate connections between objects. In this case, it is possible, for example, to display all documents of a given author along with information about his address and related documents.

Task No. 4 1. Determine what file systems are used on your hard drive workstation: · follow the main commands Windows menu: Start Þ Settings Þ Control Panel Þ Administration Þ Computer Management; · in the left pane of the Computer Management console, expand the Storage devices section and double-click on the Disk Management option; · in the right pane of the Computer Management console, information about the structure of disks and the file systems used will be displayed; · write this information in your workbook; · close the console window. 2. Determine the characteristics of logical and physical disks your workstation: · execute the commands of the Windows main menu: Start Þ Programs Þ Accessories Þ System Tools Þ System Information; · in the left pane of the System Information console, expand the Components section, and in it – the Storage devices subsection; · double click mouse select the first option Disks. The characteristics will be displayed in the right panel logical drives. Write down the meanings in your workbook; · Double-click the second option Disks. The right pane displays the characteristics of the physical disks. Write down the main meanings in your workbook; · close the console window.

NTFS New Technology File System- "new technology file system") is a standard file system designed for a family of operating systems Microsoft Windows NT.

NTFS replaced the FAT file systems previously used in Microsoft Windows and MS-DOS. NTFS supports a metadata system and also uses specialized data structures to store information about files, which improves performance, reliability, and efficient use of disk space. NTFS has built-in capabilities that allow you to limit access to data for different groups of users and individual users (ACLs - access control lists), assign quotas (restrictions on the maximum volume 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, quotas, auditing and access control, NTFS has lost the high performance of file operations inherent in HPFS. At the time of its creation, NTFS included all the latest technological advances, such as:

Ability to work with large disks. The NTFS cluster size is 512 bytes, but it can change up to 64K. Much more important quality NTFS - 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 MFT (Master File Table). MFT differs from FAT MSDOS in that it is more like a database table. If the original MFT is damaged due to a hardware error (for example, the appearance of a bad sector), the next time the system boots, the system uses a copy of the MFT, automatically creating a new original, taking into account all the damage. But this is not the main advantage. The main thing is that when writing files to NTFS disk uses a transaction system. This system comes from a DBMS, where data integrity protection is given priority Special attention, which can already say a lot about its effectiveness. This system ensures 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 cache or memory at the time of the failure and not written to disk will be lost.

Security. In NTFS, files are treated as objects. And each file object has its own properties, such as creation date, name, archived status, security descriptor, and last updated date. 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 a file, and 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 an ERD.

Data compression. Unlike DriveSpace, in which disks could only be compressed as a whole, NTFS allows you to compress separate files and catalogues. This allows you to save disk space, for example, to compress text files or large graphic files in BMP format on the fly, and all this will be transparent to the user.

ISO Unicode format support. Unlike the format ASCII, which used 7 or 8bit to encode each character, Unicode uses 16bit. For a regular user this will allow you to name files in absolutely any language, and the system will support it, without requiring you 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 supplied.

Windows NT has an 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.

File system specifications are closed. This makes it somewhat difficult for third party products that are not Microsoft to support it. For example, driver developers for free operating systems are forced to reverse engineer the system.

When you format internal storage, external hard disk, flash drive, or SD card, Windows will prompt you to select the file system FAT32, ExFAT and NTFS. But in this window there is no description of what this file system means and what the difference is between them. Therefore, in today’s article we will try to decipher these file system names.

FAT32 is the oldest file system and was introduced in Windows 95 to replace FAT16.

The age of this file system has advantages and disadvantages. Almost all flash drives you buy are purchased with the FAT32 file system, for maximum compatibility not only with computers, but also with game consoles, and other devices that support flash drives.

Limitations of this age: file size larger than 4GB FAT32 is not supported, so you can upload any number of files to the drive, but each of them should not be larger than 4GB. The maximum partition size in FAT32 is 8TB, but in operating systems Windows size The created partition in this file system does not exceed 32GB. Although if you create a partition larger than 32GB on another system, then Windows will work with the drive. But again, if you create a partition in FAT32 larger than 32GB, then according to Microsoft the performance of this disk drops significantly.

While this file system is good for flash drives, and other external drives, for internal drives this system not very good. It lacks the permissions and other security features built into the more modern NTFS file system. To install a modern Windows operating system, you need to create a partition only in NTFS.

Compatibility: Supported by all versions of Windows, Mac, Linux, game consoles and other USB devices.

Restrictions: Maximum file size 4GB, 8TB maximum partition size. IN Windows partition You can create no more than 32GB.

Perfect fit: on removable drives, for compatibility with most devices as long as you use files up to 4GB.

NTFS is the modern file system that Windows works with. All operating rooms Windows systems During installation, format the partition in NTFS. First appeared with Windows XP.

This type of file system is packed with other modern features. It supports file permissions for security, change logging, which can help you quickly recover errors if your computer suddenly reboots. It also supports shadow copies For Reserve copy, encryption, and other necessary functions.

To install a Windows system, your partition must be NTFS, and it is better to format secondary disks in this file system, for normal operation all applications.

But this file system is not compatible with other operating systems. It will work with all versions of Windows, but Mac OS X can only read disks in this file system, it cannot write to them. Also Linux only reads NTFS partitions, although some distributions have included recording support. Most game consoles do not support NTFS, but example Sony PlayStation does not support this file system, and Xbox 360 does not support it.

Compatibility: works with all versions of Windows, only reads on Mac, also Linux only reads, and not every distribution writes. Other devices are not supported by most.

Restrictions:

Perfect fit: for the system disk, and other internal disks that will only be used in Windows.

ExFat was introduced by Microsoft in 2006, and is otherwise called FAT64. Support for this file system was added with updates to Windows XP.

This file system is optimized for flash drives. One of the innovations of ExFat is the reduction in the number of overwrites of the same sector, which reduces wear on the drive.

Like NTFS, ExFat is not limited in file and partition sizes. In other words, if your drive is formatted in ExFat, then you can write files larger than 4GB to it. This file system the best choice for drives where you want a lightweight file system with no file size restrictions.

ExFat is also more compatible than NTFS if the Mac only supported read NTFS, then it fully supports ExFat, both reading and writing. ExFat can also be accessed on Linux by installing additional software.

While with operating ExFat systems more friendly, it is often not compatible with digital cameras, and not all game consoles support this file system. Yes, and other older devices may be limited to supporting only FAT32.

Compatibility: Works on all versions of Windows and modern versions Mac OS X, but requires additional software on Linux. Most older devices do not support this file system.

Restrictions: There are no restrictions on file sizes or partition sizes.

Perfect fit: For USB flash drives, external drives, etc., if you work with files larger than 4GB, and if you want to reduce wear on the drive.

NTFS is ideal for internal drives, while ExFat is more suitable for flash drives. Fat32 is mainly used for older devices that do not support other file systems.

That's all for today, if you have any additions - write comments! Good luck to you :)