We backed up Spotify (metadata and music files). It’s distributed in bulk torrents (~300TB). It’s the world’s first “preservation archive” for music which is fully open (meaning it can easily be mirrored by anyone with enough disk space), with 86 million music files, representing around 99.6% of listens.
I mean, they say earlier that music is actually well-preserved, but it’s disproportionately popular music. If the goal is then to preserve everything, I’d expect them to go for stuff that isn’t likely to be in some random audiophile’s collection or whatever then.