In their design document at https://garagehq.deuxfleurs.fr/documentation/design/goals/ they state: "erasure coding or any other coding technique both increase the difficulty of placing data and synchronizing; we limit ourselves to duplication"

Nice! Learned something new today. Seems like a way for error correction. One can store parts of data with some more metadata and if some parts of the data are lost, the original can be reconstructed via some use of computational power.

Seems like some kind of compression?

Is that how the error correction on DVD works? I

And is that how GridFS is can keep file store slow low compare to regular file system?