They use Crucible on top of ZFS. https://github.com/oxidecomputer/crucible
I don't think they have anything for S3-like service but there are other options for that, e.g. https://garagehq.deuxfleurs.fr or MinIO.
I am not sure whether they have their own SSDs or use of the shelf SSDs just with their firmware or something.
They implemented a block store with replication from scratch? That's kinda brave, considering that that's a project big enough to justify full startups for!
However, the folks at Oxide are at the top of the game for this space with dozens of years of experience in building and testing such systems. Secondly Oxide's crucible stack is completely written from scratch in Rust, which dramatically reduces failure modes common to such stacks, which are often written in C / C++.
