Why is deduplication not supported in ext4?

[ravish165]

Deduplication feature is not supported in ext4 but it is in btrfs.

Being a stable and mature linux file system, what is the reason of not providing the feature in ext4.

Is it in the roadmap of ext4?

[Flash]

Um, well, there's probably an ext4 forum or mailing list or something, where you can ask the developers and maintainers of ext4 why it doesn't support deduplication, whatever that is.

[Burn_IT]

Deduplication is where the file system replaces repeated data with a pointer to the earlier occurrence.
It is used heavily in things like zipping where speed of execution is traded with file size.
I would imagine that where a file system needs/tries to be fault tolerant then deduplication would not be a good thing.

BTRFS is a lot newer design and has better fault tolerance built into the base design, however I suspect deduplication only occurs across files and not so heavily within files.