" ... This the Chiron Filesystem. It is a Fuse based filesystem. It's main purpose is to guarantee filesystem availability using replication. But it isn't a RAID implementation. RAID replicates DEVICES not FILESYSTEMS. .. " -- seems to offer fs-level replication, but again, the details on recovery after volumes have gone out of sync are scarce. It looks like the right idea with the wrong execution.

" ... Gluster simplifies the task of storing massive amounts of unstructured data. GlusterFS is an open source clustered file system that runs on commodity hardware, delivering greater scalability and performance at a fraction of the cost of conventional storage. ... " -- other than that, they do seem to offer fs-level data replication, although it's entirely unclear how it's implemented.