Comment by londons_explore
13 hours ago
Google internally has lots of possible redundancy levels for data.
They don't sell any of the lower and less reliable levels to the public, I suspect simply because the reputational damage from losing user data is so bad, and the news will take no notice of the fact the user got a discount for less reliable storage.
Most of Google's customers wouldn't know how to choose anyways, if these were exposed. My memory was quite hazy but I recall having a discussion with my colleague on choosing which Reed–Solomon code for our Colossus files, and apparently the choice was down to RS(8,3) or RS(9,3). I don't think even as Googlers we really had enough information to make an informed choice. Comparatively it was much easier to decide which cells to use for multi-location replication in Placer.