Fascinating. If this had been around a year ago, we could have used it in our datacenter build-out. For data source reasons, we record data in the cloud. In the past, we'd stick most of the data in S3 and only egress what we needed to run analysis on. The way we'd do that is that we have a machine with 16 * 30 TiB SSDs that acts as our on-prem cache of our S3 data. It did this using a slightly modified goofys with a more modified catfs in front of it, with both the cache and the catfs view exported over NFSv4. We had application-level switching between the cache and the export since our data was really read-only.

When the cache got full, catfs would evict things from it pretty simply. It's overall got a good design but has a few bugs you have to fix, and when you have 100 machines connecting to it, it requires some tuning to make sure that it doesn't all stall. But it worked for the most part.

Anyway, I think this is cool tech. I'm currently doing some bioinformatics stuff that this might help with (each genome sequence is some 100 GiB compressed). I'll give it a shot some time in the next couple of months.