Interesting! We have been doing the same thing with HopsFS for a couple of years. Except, we only store the small files in our database (www.rondb.com) - RonDB is a recent fork of MySQL Cluster (NDBCluster). Very small files (<1KB) are stored in memory in RonDB, small files (typically <128KB) are stored in NVMe disks in RonDB, and other files in HopsFS (which now stores its blocks in object storage (S3, ABS).

We had a paper on it as ACM Middleware and it's open-source on github. Are you going to publish your solution?

(Discussed here on HN: https://news.ycombinator.com/item?id=25149154 )