File Systems

✅ What is a File System?

A file system is a method of organizing, storing, retrieving, and managing data on storage devices like hard drives (HDD), solid-state drives (SSD), USB drives, and memory cards.

It defines how data is stored and how files and directories are named, accessed, and protected.

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🔑 Key Functions of a File System:

Function	Description
Data Organization	Structure for storing files and directories (folders).
File Naming	Rules for file names and extensions.
Storage Management	Manage free and used space on storage devices.
Access Control	Define permissions and user access to files.
Security & Integrity	Protect files from corruption and unauthorized access.

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🗂️ Common Types of File Systems

File System	Used In	Key Features
FAT32 (File Allocation Table)	USB drives, older systems	Simple, compatible with Windows, macOS, Linux; file size limit 4 GB.
exFAT (Extended FAT)	USB drives, SD cards	Supports large files (>4 GB), cross-platform, optimized for flash drives.
NTFS (New Technology File System)	Windows OS (default)	Advanced security, large file support, compression, encryption.
HFS+ (Hierarchical File System Plus)	Older macOS versions	Used before APFS, supports large files, journaling.
APFS (Apple File System)	Modern macOS, iOS	Optimized for SSDs, encryption, cloning, snapshots.
ext3 (Third Extended File System)	Linux	Journaling, better performance and reliability.
ext4 (Fourth Extended File System)	Linux (default)	Improved performance, large file support, journaling.
Btrfs (B-tree FS)	Linux (newer systems)	Advanced features like snapshots, compression, self-healing.

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📊 Comparison of Major File Systems

Feature	FAT32	exFAT	NTFS	ext4	APFS
Max File Size	4 GB	16 EB	16 TB+	16 TB+	8 EB
Max Volume Size	8 TB	128 PB	256 TB	1 EB	8 EB
Journaling	No	No	Yes	Yes	Yes
Security (ACL)	No	No	Yes	Yes	Yes
Compatibility	Most OS	Most OS	Windows	Linux	Apple OS
Encryption	No	No	Yes (BitLocker)	Yes (LUKS etc.)	Yes

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🛠️ Windows File Systems Overview:

File System	Purpose
FAT32	Legacy support, small drives, bootable media.
exFAT	External drives, compatible across OS.
NTFS	System drives, internal storage, Windows installs.

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🧑‍💻 Linux File Systems Overview:

File System	Purpose
ext4	Default for modern Linux distros.
ext3	Older systems, backward compatible.
Btrfs/ZFS	Advanced systems needing snapshots, checksums.

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🍏 macOS File Systems Overview:

File System	Purpose
APFS	SSDs, modern macOS.
HFS+	Legacy, older Macs.
exFAT	For drives shared with Windows.

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🔒 File System Security Features:

Feature	File Systems Supporting It
Permissions (ACL)	NTFS, ext4, APFS
Encryption	NTFS (BitLocker), ext4 (LUKS), APFS (native)
Journaling	NTFS, ext4, APFS
Compression	NTFS, Btrfs

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⚙️ Formatting a Drive with a File System:

• Windows:

  • Use Disk Management (GUI) or Command Line (diskpart).

  • Format as NTFS, exFAT, FAT32.

• Linux:

  • Use GParted (GUI) or Command Line (mkfs).

  • Format as ext4, ext3, Btrfs, XFS.

• macOS:

  • Use Disk Utility (GUI).

  • Format as APFS, HFS+, exFAT.

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📥 Command Examples (CLI):

OS	Command	Purpose
Windows	format D: /FS:NTFS	Format D: drive as NTFS.
Linux	mkfs.ext4 /dev/sdb1	Format device as ext4.
macOS	Use Disk Utility or diskutil eraseDisk APFS MyDisk /dev/disk2	Format as APFS.

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🧠 Key Things to Remember:

• FAT32: Great for compatibility but limited in file size.

• exFAT: Good for large files and cross-platform use.

• NTFS: Best for Windows system drives.

• ext4: Default for Linux, reliable.

• APFS: Modern Mac file system, optimized for SSD.

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✅ Summary Table:

Purpose	Recommended File System
Windows system drive	NTFS
USB drive (cross-platform)	exFAT
Linux system drive	ext4
Mac system drive (SSD)	APFS
Large file storage	exFAT, NTFS
Data backup on Linux	ext4, Btrfs