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File system

technology Maturity 11-13 Next article →

A file system is a very important part of a computer. It is a system that manages how files are organized and accessed. Think of it as a digital manager for your data. This manager works within the operating system to help different applications. It also helps networked computers share files with each other. Without this system, applications might try to use storage in ways that clash. This could lead to data corruption or even losing your files entirely.

File system fragmentation
File system fragmentation

How does this digital manager work? It uses different layers to handle your data. The first layer is called the logical file system. This layer uses an application programming interface, or API, to handle tasks like opening, closing, reading, and writing files. It also manages security and keeps track of which files are currently open. Below that is the physical file system layer. This layer talks directly to the storage device, like a hard disk. It handles the small details like writing data blocks and managing memory.

Dir command in Windows Command Prompt
Dir command in Windows Command Prompt

People have been using the idea of filing systems for a long time. Before computers existed, people used filing systems to organize paper documents. By the year 1961, the term was used for computerized filing. By 1964, the term was being used by almost everyone. Today, file systems work on many different types of storage. They work on hard disk drives (HDDs) and solid-state drives (SSDs). They also work on magnetic tapes and optical discs. Some systems even use a part of the computer's main memory as a storage device.

100 000-files 5-bytes each -- 400 megs of slack space
100 000-files 5-bytes each -- 400 megs of slack space

File systems use many specific tools to keep things tidy. They use file names to identify exactly which file an application needs. These names are usually unique within a single directory. Directories, which are also called folders, help group files together. Some systems allow for a hierarchy, where folders live inside other folders. Many famous systems use these structures, like NTFS in Windows or HFS+ on older Macs. The system also tracks metadata, which is extra information about a file. This includes the file size, the date it was last changed, and who owns it.

Btrfs qgroup screenshot
Btrfs qgroup screenshot

Managing space is another big job for the file system. It tracks which areas of a disk are full and which are empty. When you delete a file, the system marks that space as free to use again. Sometimes, a file might not fit perfectly into the storage blocks. This creates tiny bits of unused space called slack space. Over time, files might also become fragmented. This happens when a file is split into pieces instead of staying in one solid block.

File system fragmentation
File system fragmentation

While fragmentation can slow down some hard drives, it does not affect solid-state drives.

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🖼️ Images & Media (4)
File:100 000-files 5-bytes each -- 400 megs of slack space.png
100 000-files 5-bytes each -- 400 megs of...
File:File system fragmentation.svg
File system fragmentation.svg
File:Btrfs qgroup screenshot.png
Btrfs qgroup screenshot.png
File:Dir command in Windows Command Prompt.png
Dir command in Windows Command Prompt.png
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