I'm betting this is on the front page today (as opposed to any other day; Juice is very neat and doesn't need us to hype it) because of our Sprites post, which goes into some detail about how we use Juice (for the time being; I'm not sure if we'll keep it this way).
The TL;DR relevant to your comment is: we tore out a lot of the metadata stuff, and our metadata storage is SQLite + Litestream.io, which gives us fast local read/write, enough systemwide atomicity (all atomicity in our setting runs asymptotically against "someone could just cut the power at any moment"), and preserves "durably stored to object storage".
Litestream.io is amazing. Using sqlite as a DB in a typical relational data model where objects are related mean most read then write transactions would have to one node, but if the using it for blobs as first class objects(e.g. video uploads or sensor data) which are independent probably means you can shard and scale your set up the wazoo right?
The TL;DR relevant to your comment is: we tore out a lot of the metadata stuff, and our metadata storage is SQLite + Litestream.io, which gives us fast local read/write, enough systemwide atomicity (all atomicity in our setting runs asymptotically against "someone could just cut the power at any moment"), and preserves "durably stored to object storage".