Well, the poster probably meant whatever GFS incarnation is around these days (Colossus is v2 or v3, depending on how you look at things). In the end, almost everything at Google is backed by "GFS": Bigtable, Blobstore, GCS, Spanner, Megastore, etc. There's little else that is not backed by GFS, but talks to D directly. At least that has been mentioned in public, of course. Still, none of it is user facing/serving, though.