EXT and other filesystems

Question

Is it true only NTFS needs to be defragmented?

Are filesystems like ext4, 3 and 2 immune to fragmentation issues. Apple never seems to require a defragmentation so what makes some filesystems immune to fragmentation?

Answer 1

NTFS is not alone, but it is the most prone of the popular modern filesystems.

As per the Linux System Administrator Guide:

"Modern Linux filesystem(s) keep fragmentation at a minimum by keeping all blocks in a file close together, even if they can't be stored in consecutive sectors. Some filesystems, like ext3, effectively allocate the free block that is nearest to other blocks in a file. Therefore it is not necessary to worry about fragmentation in a Linux system."

This does not mean that the ext3 or ext4 filesystems are immune to the issue; it's just that they're better managed. It might still be required over an extended period of usage or for specific usage patterns.

Ref: ext3 - Wikipedia, the free encyclopedia