File System Types Overview (FAT, NTFS, ext4)
- Process Management
- Memory Management
- Deadlocks
- OS Introduction & Fundamentals
- CPU Scheduling Algorithms
- Threads & Concurrency
- Inter-Process Communication (IPC)
- Process Synchronization
- Virtual Memory & Paging
- File Systems
- Disk Scheduling
- I/O Management
FAT: A Simple, Widely Compatible Older Design
FAT (File Allocation Table) uses a table listing which blocks belong to each file, essentially a table-based variation of the linked allocation approach covered in the file allocation methods note. It's simple and extremely widely supported across virtually every operating system, which is exactly why it remains common on USB drives and SD cards today, despite lacking many features of newer file systems.
NTFS: Windows's Modern File System
NTFS (New Technology File System) is the default file system on modern Windows, offering features FAT lacks entirely - detailed file permissions, journaling (recording pending changes before actually committing them, so the system can recover cleanly after a crash), and support for much larger files and volumes than FAT allows.
ext4: A Common Choice on Linux Systems
ext4 is a widely used Linux file system, also supporting journaling, along with large file/volume support and various performance optimizations. It represents an evolution of earlier ext-family file systems, refined for better reliability and performance over time.
Comparing the Three at a Glance
| FAT | NTFS | ext4 | |
|---|---|---|---|
| Common platform | Universal - USB drives, cameras, etc. | Windows | Linux |
| Journaling | No | Yes | Yes |
| Detailed permissions | No | Yes | Yes |
| Max practical file/volume size | Limited | Very large | Very large |
What Journaling Specifically Protects Against
Without journaling: a crash mid-write can leave the file system in a corrupted, inconsistent state
With journaling: the intended change is recorded first (the "journal"), then applied -
if a crash happens mid-way, the system can replay or safely undo the journal entry on restartJournaling records an intended change before actually performing it, so if a crash happens partway through, the file system can recover to a consistent state by replaying or discarding the incomplete journal entry - a major reliability improvement over older, non-journaling file systems like plain FAT.
Why the File System Choice Genuinely Matters
Choosing a file system isn't purely academic - it directly affects compatibility (does every device you need to use it with actually support this format?), reliability (does it protect against corruption after a crash?), and performance for a given real-world workload.