What is File System – What is File System
Everything in each computer system is stored according to the files. These files are mainly either data files or application files. Each operating system has its own way of organizing data internally.
The operating system here performs this management with the help of a program called the File System. Here the type of file system determines how to access data and programs. In addition, it also determines which level of accessibility is available to the users.
What are file systems?
In a computer, a file system – written as filesystem – is a method where files are named and where they are placed logically for storage and retrieval.
Without a file system, it is difficult to isolate stored information in individual files and in such a situation it becomes even more difficult to identify and retrieve them. As data capacities increase, then their organization and accessibility of individul files become more important in data storage.
Digital file systems and files have been named and modeled in such a way that only after paper-based filing systems can they store and retrieve documents using the same logic-based method.
File systems are different in different operating systems (OS), such as Microsoft Windows, macOS, and Linux-based systems. Some file systems are designed for certain specific applications. Major types of file systems are distributed file systems, disk-based file systems and special-purpose file systems.
Architecture of the file system
Each File System has two or three layers. Sometimes all the layers in the File System are explicitly separated, and sometimes the functions of all the layers are combined into one layer. It depends on that task how to do it.
1. Logical file system – This file system is related to the user application, such as an application program to open (OPEN) the file and read (READ) its data and then the application program to close (CLOSE) the file. Provides the Application Program Interface. This layer provides file access, directory related tasks and security related operations.
2. Virtual file system (optional) – This layer is not required to be present in every file system, this layer is used to manage virtual files.
3. Physical file system – This layer is related to the physical operation of a storage device (such as a disk). It processes the physical blocks to be read or written. It handles buffering and memory management and is responsible for the physical location of blocks in specific locations on the storage medium. The physical file system interacts with the device drivers or with the channel to run the storage device.
How do file systems work?
A file system that stores and organizes data, we can understand the type of an index that indexes all the data of the storage device. These devices can be anything like hard drives, optical drives and flash drives.
File systems specify many things such as naming of files, placing the maximum number of characters in a name, which characters can be used, and many more. Because file names in many file systems are not case sensitive.
Along with the file, file systems also hold many different information such as the size of the file, its attributes, location and hierarchy directory, and also in metadata.
Metadata can easily identify the available storage of free blocks and how much space is available in that drive right now.
A file system also includes a format that specifies the path of the file to the structure of its directory. A file is placed in a directory – or in a folder of Windows OS – or in a desired structure of a subdirectory in a tree structure.
Files are placed in the file systems of PC and mobile operating systems in a hierarchical tree structure.
Before creating files and directories in Storage Medium, partitions must be put in the correct places first. A partition is a region of hard disk or any other storage that the OS manages separately.
A file system is placed in the primary partition, and some OSes allow multiple partitions on the same disk. In such a situation, if one file system is corrupted, then the data in another partition is completely safe.
Types of file systems (according to Operating Systems)
By the way, there are many types of file systems, all of which have different logical structures and properties, such as speed and size. These file system types may be different according to OS or according to OS requirements.
The three most common PC operating systems are Microsoft Windows, Mac OS X and Linux. The Mobile Operating System includes Apple iOS and Google Android.
Right here We will only know about these major file systems:
1. File allocation table (FAT)
It supports the File System Microsoft Windows OS. FAT is considered very simple and reliable, and has been modeled only after legacy file systems.
The FAT was designed in 1977 for floppy disks, but was later adapted to hard disks. While it is very efficient and compatible with almost all current OSes, FAT cannot match with modern file systems of today if their performance and scalability are compared.
2. Global file system (GFS)
This file system is mainly used in Linux OS. It is a shared disk file system. GFS offers direct access to shared block storage and together it can be used according to a local file system.
GFS2 is an updated version of Original GFS, it has features that you may not see in the original GFS, such as an updated metadata system. Under the GNU General Public License, both GFS and GFS2 file systems are available according to a free software.
3. Hierarchical file system (HFS)
These HFS were developed to be used in Mac operating systems. HFS is referred to by a Mac OS Standard, followed by Mac OS Extended.
It was originally introduced in 1985. For the same floppy and hard disks, HFS completely replaced the original Macintosh file system. At the same time it can also be used in CD-ROMs.
Types of Windows File System
Likewise, there are many types of Windows File Systems, but some of them are very important. So let’s know about them.
1. FAT File System
The full form of FAT is “File Allocation Table”. File Allocation Table (FAT) is a file system created by Microsoft in 1977.
This file allocation table is used by the operating system to locate files in the disk. A file can be divided into many sections and can also be scattered due to fragmentation around the disk. The FAT keeps track of all pieces of a file.
In DOS systems, FAT is stored after the boot sector. The use of these file systems started happening more after the arrival of PC.
FAT is still used for a preferred file system, as well as floppy drive media and portable, high capacity storage devices such as flash drives and other solid-state memory devices such as SD cards.
What are the features of FAT File System?
Let us now know about some important features of the FAT File System
1. The FAT file system that was used by MS-DOS provided only the file name with 8 characters long.
2. The FAT file system used by Windows 2000 used to support long filename.
Here, they used to support the full path of file including filename for about 255 characters long.
3. It can use any character in file names except “/  =, ^? A” “
4. File names must begin with an alphanumeric characters.
5. File names can use spaces and multiple periods. In this, the characters after the last period are also treated as file extensions.
FAT neither provides local nor folder security. A user who is logged on to the computer locally then has full access to all the files and folders that are in the FAT partitions of the computer.
Quick Access to Files
FAT provides quick access to files. The speed of file access depends on the file type, file size, partition size, fragmentation and number of files that are in the folder.
2. FAT32 File System
FAT32 is an advanced version of the FAT file system. It can be used in drives whose memory is in the size of 512 MB to 2TB. A very important feature is that it offers compatibility of FAT and FAT32 with other operating systems which is not different from Windows 2000.
What are the features of FAT32 File System?
Let us now know about the features of FAT32,
FAT32 increases the number of bits used to address the cluster.
A cluster set of sectors is called. They reduce the size of each cluster. It supports larger disk (up to 2TB) and provides better storage efficiency.
FAT32 provides better file access, in partitions whose sizes are less than 500 MB or larger than 2GB, it provides better disk space utilization.
Types of FAT File Systems
There are also many types of FAT File Systems, let’s try to know about them.
FAT12 (12-bit File Allocation Table)
This was a much used version of the FAT file system. The FAT12, was introduced in 1980, right alongside the earlier versions of DOS.
FAT12 is the primary file system of Microsoft Operating Systems up to MS-DOS 3.30 but was also used later.
Or in MS-DOS 4.0. Using FAT12, you can probably see it in a floppy disk.
FAT12 supports drive sizes and file sizes up to 16 MB in which they use 4 KB clusters or 8 KB clusters in 32 MB. The maximum number in a single volume can be 4,084 files (when we use 8KB clusters).
File names that fall under FAT12 cannot exceed the character limit (8 characters), plus 3 for extension.
In FAT12, many file attributes were first introduced which are hidden, read-only, system, and volume label.
FAT16 (16-bit File Allocation Table)
The second implementation of FAT was FAT16, which was introduced in 1984 in PC DOS 3.0 and MS-DOS 3.0.
At the same time a slightly more improved version of FAT16, it was named FAT16B, became the primary file system from MS-DOS 4.0 to MS-DOS 6.22.
At the beginning of MS-DOS 7.0 and Windows 95, a further improved version, called FAT16X, began to be used.
Looking at the operating system and the cluster size used, the maximum drive size ranges from a FAT16-formatted drive to 2 GB to 16 GB, while the latter is only used in Windows NT 4 with 256 KB clusters. .
In FAT16, the file size drives up to max 4 GB with Large File Support enabled, or only 2 GB without it.
The maximum number of files that can be held in a FAT16 volume are 65,536. As with FAT12, file names are placed in the limit of 8 + 3 characters but can be expanded to 255 characters with Windows 95.