Understanding a Computer File System

File systems are the structures behind how your computer stores and organizes data. Everything you install, save, edit or create on your computer comprises the trillions of bits of data a file system stores, organizes and allows access to on a daily basis for computer users. Hard drives, CD-Roms, DVD-Roms and servers are all types of file systems that allow you access to data.

File systems do not necessarily need a physical way to organize data. While most people are familiar with the file systems on their hard drive, virtual file systems exists to organize information on servers and the world wide web as well. Most file systems are organized in sections of 512 bytes where the file system software organizes, categorizes and makes available data in each of those sectors. Software will know at any given time where a particular data node is stored and how to access it instantly.

All file systems sort information into some sort of directory for easy access. Some systems create very detailed structures where others keep files in an organized disarray. Depending on the type of file system software you are running, navigating the nodes of information can be easy or difficult for the average computer user. The average computer user relies on their operating system to take care of the file system for them, and in most cases, this is all that is necessary for the computer user. More advanced user may find the organization of their data to benefit from a different type of file system all together.

Most file systems can create, move and delete files and directories similar to how you would delete a whole folder in Windows XP. You can simply drag and drop the folder into the trash can, and it is gone. In MS-DOS, you use a sequence of commands to eliminate a folder from the system. Other UNIX-based file system structures allow you further abilities to modify data without diving into the advanced realm of computing. You can also limit who has access to what functions, such as creating or editing files, via file system software within the confines of your operating system.

Most file systems can be classified into three different types: Disk, network and special purpose. Disk file systems are designed to store information on a hard drive disk. FAT, NTFS and UDF are all types of disk file systems. Network file systems act as a client for file access protocols on a server. FTP, WebDAV and NFS are types of network file systems. Special purpose file systems are the miscellaneous systems that do not fit into the disk or network file system categories. Special purpose systems are generally used in Unix-based systems. Flat file systems are one of the most general ways to store data. Information is stored on the same level instead of creating sub-levels of data.

There are sub-categories of file systems as well. Database file systems, for example, identify files by their type, author or other meta data. Transactional file systems log the access of files by individuals in the hopes of executing all changes at the same time; banks and financial institutions employ this type of file structure in their computer systems to ensure the seamless transfer of money between two accounts and other functions that require autonomy.

Operating systems provide a basic type of file system. Early computers used DOS as the focal point of their file system and over time, programs like Windows, Mac OS and Linux have developed their own file system for computer users. These operating system interfaces give users the opportunity to do what they want on their computer without worrying about the complicated mess of a file system to maintain. The OS will maintain it for them and with little to no learning curve.

Within Unix and Unix-based operating systems, each device has a name. Unix creates a virtual system and makes everything look like it runs on the same level when in fact it is navigating a more complex structure of data. There is one root directory, and everything will be confined to that directory for you while your computer scatters the data across its virtual system.

If you want to access another device or root directory, you must let your OS know where that directory is. This is called mounting. Only an administrator should be allowed to mount a file system, and only advanced computer users should attempt the process.

Windows was created from MS-DOS and uses the File Allocation Table (FAT) and New Technology File System (NTFS) to organize data. NTFS was introduced when Microsoft released the NT version of Windows. Microsoft uses a drive letter to designate the root directory of a computer. Most users will see the C:\ as their primary directory when booting their computer. In computer history, the A:\ and B:\ were designations for the two types of floppy drives that existed during the time. All sub-directories and files are represented by graphics that a user can click on and modify on a whim.

Under the Mac operating system, most notably X, HFS Plus is used as the primary file system. It is considered a case preserving system and Unix permissions were developed for it. HFS Plus employs Unicode to encode files and uses a number of optimization techniques to preserve data in a speedy and efficient manner. It also makes use of hard links, symbolic links and aliases to link files within the whole system. Mac OS X is unique in that it uses both Mac-based protocols and Unix-based link structures to operate its file system.

Each file system has its own pros and cons, and most users are familiar with the Microsoft Windows platform as their only introduction to their computer's file system. File systems are meant to make your life easier, and operating systems are the software that helps you navigate through it without having to go to too much trouble to organize your files on your own.