I came across Seaweed FS, which I think is perfectly architectured:
- Acknowledgement of existence of other technologies, so master metadata can be stored in Redis(Cluster), Cassandra, Etcd
- Any use case I could think of covered — FUSE mount, HDFS, S3 API gateway, WebDAV, Async Backup into the cloud
- Tiered Storage.
- Cross-Datacentre replication (I don’t need it at home, but the number of databases/storages supporting cross DC replication out of the box can be counted on one hand)