[toolslive]

It's not really "redundant copies". It's erasure coding (ie, your data is the solution of an overdetermined system of equations).

[christina97]

That’s just fractional redundant copies.

[Dylan16807]

And "fractional redundant copies" is way less obvious.

[crazygringo]

The fractional part isn't helping them serve data any faster. To the contrary, it actually reduces the speed from parallelism. E.g. a 5:9 scheme only achieves 1.8x throughput, whereas straight-up triple redundancy would achieve 3x.

It just saves AWS money is all, by achieving greater redundancy with less disk usage.