Originally posted by [deXter]
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F2FS doesn't have useful space saving compression, it has write endurance saving compression. Whatever compression that is accomplished only saves the amount of writes done to the storage, the free blocks and bitmap are still factor in the uncompressed size, meaning you save no space. With a perfect 2x compression ratio a 256GiB drive using F2FS can have 256GiB of data loaded onto it before it reports itself as full, but only 128GiB of compressed data is written.
It's possible to reclaim the overwrite, however doing so makes the compressed files immutable, relegating this to only being useful for cold storage write-once.
The claim of compression increasing read throughput is really only applicable for scenarios where the scale between CPU power and bus speed/storage speed is lopsided in favor of the CPU. Situations with a modern processors being attached to garbage bin SSDs or eMMC/SD cards.
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