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This article mainly explains "what are the differences between ext4 and ext3 in linux". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the differences between ext4 and ext3 in linux?"

Differences: 1, ext3 has 32000 subdirectories, while ext4 has unlimited; 2, ext3 uses indirect block mapping, which is inefficient when operating large files, ext4 uses Extents, and each Extent is a group of continuous data blocks with high efficiency; 3, ext3 allocates only one data block at a time, while ext4 can allocate multiple blocks at a time.

The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is the difference between ext4 and ext3 in linux

A file system is a method of organizing files on storage devices such as disks. Linux system can support a variety of popular file systems, including: EXT2, EXT3, EXT4, FAT, FAT32 and so on. So what's the difference between ext3 and ext4 in Linux system?

1. Larger file systems and larger files

Ext3:16TB file system and maximum 2TB file

Ext4:1EB file system and maximum 16TB file.

2. Unlimited number of subdirectories

Ext3:32000 subdirectories

Ext4: an unlimited number of subdirectories.

3 、 Extents

Ext3: indirect block mapping is used, which is extremely inefficient when manipulating large files. For example, for a 100MB-sized file, a mapping table of 25600 blocks is created in ext3.

Ext4: the concept of Extents is introduced. Each Extent is a set of contiguous data blocks. The above file represents that the file data is saved in the next 25600 data blocks, which improves a lot of efficiency.

4. Multi-block allocation

Ext3's block allocator can only allocate one 4KB block at a time. Writing a 100MB file requires 25600 calls to the block allocator, while ext4's multi-block allocator multiblock allocator supports one call to allocate multiple blocks.

5. Delayed allocation

Ext3's block allocation strategy is to allocate as soon as possible, while ext4 delays allocation as much as possible, and does not start allocating blocks and writing to disk until the file has been written in cache, so that block allocation for the entire file can be optimized and performance can be significantly improved when combined with the first two features.

6. Related characteristics of inode

Ext3:128byte

Ext4:256byte .

Thank you for your reading, the above is "what is the difference between ext4 and ext3 in linux". After the study of this article, I believe you have a deeper understanding of the difference between ext4 and ext3 in linux, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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