What Is A Journaling File System, And How Does It Work?

What Is A Journaling File System, And How Does It Work?


How do you store your stuff? Personally, I just dump my stuff wherever I find space in my room. And for the new things, I make space somewhere near to me by dropping all old stuff somewhere. Unfortunately, a computer cannot store files folder somewhere and everywhere. It has to keep all the data in an organized manner so that any file that is called upon can be accessed in no time. Another example of an organized file system is the library where all books are indexed and categorized.

Similarly, every operating system has its own unique journaling file system to maintain its data. With a lot of differences between the journaling file systems, there is one feature that is common among them, and that is Journaling.

What Is Journaling File System?

The word Journal represents maintaining time-based events in a diary. Similarly, Journaling in computers indicated that all files are stored with an entry in the relevant catalogue, and any changes are documented in the computer’s own journal. When you search for a file on your computer, it does not scan the entire hard disk for that file; instead, it checks the relevant catalogue.

Journaling does not necessarily mean that files store in the same hard drive sector are bundled in one catalogue. Two files stored far apart can have their entries in the same catalogue. This helps the computer to access them faster as it does not scan every file on your hard drive but scans through the journal entries and locate the required file.

What Are The Units Used in a Journaling File System?

As discussed earlier, there are different types of journaling file systems, but they all use the same type of units of measurement. I have mentioned them in brief in the table below:

Unit Name Short form Value
Tebibytes TiB 1024 gigabytes
Pebibyte PiB 1024 tebibytes

Also read: Know All About Batch File

1. New Technology File System – Microsoft

New Technology File System – Microsoft

Microsoft has developed its own journaling file system known as New Technology File System or NTFS for short. This has been used by default in all Windows operating systems as it supports large data volumes. The maximum file size supported 256 TiB, which is very large indeed, and you probably have never encountered a file that large.

NTFS uses checkpoint information and log files to re-establish the constant values of a file structure after a restart. It can also fix corrupted files through what is known as Self-Healing NTFS without any occurring downtime. NTFS was developed over the FAT32 file system and can read, write and search faster than most systems.

2. Extended File System – Journaling in Linux

Extended File System – Journaling in Linux

Like Microsoft, Linux has its own journaling file system and is called the Extended File System or EXT. It was based on the earlier Unix mode or UFS but has gone through three upgrades in recent years. The Extended File System or EXT has 4 versions in all with a number added to the newer version.

EXT 2: This Journaling system in Linux was used in Red Hat Linux initially and is still used in SD cards and USB drives. It has a maximum capacity of 32 TiB, which is very less as compared to other journaling file systems.

EXT 3: There is not much difference between EXT 2 and EXT 3. However, EXT 3 has become more popular and used in Linux, BSD, and ReactOS.

EXT 4: Due to the limitations of EXT 2 and EXT 3, the need for a new journaling file system was apparent, and EXT 4 was developed, which has a maximum size limit equal to 1024 PiB or a million TiB. It is used by most Linux distributions today and even by Google File Storage and Power PC. EXT 4 has inculcated the feature of using checksums in the journaling file system to improve reliability and performance.

Also Read: 7 Best Open Source Cloning Software for Linux

3. Apple File System -Apple

Apple File System -Apple
Image Source: Apple

Apple File System or APFS for short, is a journaling file system used by Apple in its macOS computers. It was rolled out with Sierra and iOS 10.3 and supports 8000 PiB, which is higherthan EXT4 that supports 1024 PiB only.

APFS has inculcated the full disk encryption, and it facilitates capturing snapshots of the system, which is then used for reference. It also uses checksums to ensure data integrity and protects the system from crashing.

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The final word on Journaling File System

Journaling in file systems is an important feature that helps during unexpected shutdowns and system crashes. The journaling file system maintains a ledger system concerning every file and every change being recorded. This makes it easy to locate and execute any file when a command is sent. I hope you like the information shared on this article, and do subscribe to our Facebook Posts and YouTube Channel for more articles like these.

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