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.
🔑 Key Functions of a File System:
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.
🗂️ Common Types of File Systems
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.
📊 Comparison of Major File Systems
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
🛠️ Windows File Systems Overview:
FAT32
Legacy support, small drives, bootable media.
exFAT
External drives, compatible across OS.
NTFS
System drives, internal storage, Windows installs.
🧑💻 Linux File Systems Overview:
ext4
Default for modern Linux distros.
ext3
Older systems, backward compatible.
Btrfs/ZFS
Advanced systems needing snapshots, checksums.
🍏 macOS File Systems Overview:
APFS
SSDs, modern macOS.
HFS+
Legacy, older Macs.
exFAT
For drives shared with Windows.
🔒 File System Security Features:
Permissions (ACL)
NTFS, ext4, APFS
Encryption
NTFS (BitLocker), ext4 (LUKS), APFS (native)
Journaling
NTFS, ext4, APFS
Compression
NTFS, Btrfs
⚙️ 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.
📥 Command Examples (CLI):
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.
🧠 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.
✅ Summary Table:
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
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