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Understanding File Systems: Storage, Organization, and Management of Digital Data

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In computing, a file system is a method for storing and organizing computer files and their data, enhancing accessibility and management. It serves as a special-purpose database for data storage, manipulation, and retrieval. Various types of media like HDDs, USB drives, and tapes require a file system for consistent data access. Key features include directory organization, access control, and data encryption. Understanding concepts like encryption, compression, and file allocation mechanisms such as FAT and NTFS is crucial for optimizing data management and storage efficiency.

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Understanding File Systems: Storage, Organization, and Management of Digital Data

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  1. T111 File Systems

  2. File Systems • “In computing, a file system (often also written as filesystem) is a method for storing and organizing computer files and the data they contain to make it easy to find and access them…”“…More formally, a file system is a special-purpose database for the storage, organization, manipulation, and retrieval of data.”Wikipedia

  3. File Storage • Files can be stored on: • HDD • Optical media • Flash media (USB drives / SSDs) • Tape • Floppy • Which of these require a file system?

  4. File Systems • Why have them? • To have a consistent way to access data in storage regardless of the storage media • So that the programmer does not need know how to access various different types of storage

  5. File Systems • File Systems may provide: • Allow files to be organised into logical directories • Access control • Procedures for copying moving and deleting • Encryption • Compression

  6. Encryption • Encrypts files so that they are unreadable by unauthorised users • Uses an algorithm (Cypher) to encrypt plain text and make it unreadable • Advantage • Files are protected and only accessible by authorised users • Disadvantage • Requires more processing time than files that are not encrypted to read / write

  7. Encryption • When would you use encryption? • When would you not use encryption?

  8. Compression • Compresses files so they take up less storage space • Works better on some files than others • Advantage • Files take up less space • Disadvantage • The files have to be decompressed before they are read and then compressed before they are written

  9. Compression • When would you use compression? • When would you not…?

  10. HDD Terminology B A C A D C (Sector is usually the same as block) Geometrical Sector Cylinder Block Track Cluster Track Sector

  11. HDD Terminology • Block • The smallest accessible part of a HDD • Cluster • A defined group (cluster) of blocks • Cluster size can be configured when the partition is formatted

  12. File Systems • The file system allocates files to clusters rather than blocks • Therefore, a 1 byte file will take up 1 cluster even if the block size is 512bytes • Does this seem like a waste?

  13. File Systems • Small files or files that only use a small part of a cluster waste storage space • Why not make the cluster size one block? • As the cluster size increases, file fragmentation decreases • Less file fragmentation means faster file access and vice versa • The more clusters there are, the more there are to manage • The file system structure is cached into RAM so that it can be read quickly • The smaller the cluster size, the larger the file system structure that has to reside in RAM • HDD space is always cheaper than RAM

  14. File Allocation Table (FAT) • A simple file system • Supported by mp3 players, digital cameras etc • Not implemented for PCs any more • FAT16 • Supports 2GB partition size • FAT32 • 2TB disk size (in theory) • 4GB maximum file size

  15. FAT • The good: • Simple and widely supported • Suitable for smaller drives • The bad: • Has limiting file size restrictions • Becomes very inefficient and slow when used on large partitions / drives • Windows won’t even let you create a partition over 32GB • The ugly: • Easily becomes fragmented • Everyone now thinks that they need to defrag their NTFS drives every month

  16. File System Exercise

  17. NTFS • New Technology File System… next week

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