Hi!
Will it somehow work: probably, at least in a wider sense.
Will it make problems, result in poorer performance and even
maybe to subtle errors where no one can really help: highly probable.
I like the idea of the CEPH drives having extra redundancy.
Ceph
is the redundancy! At least it should be.
Ceph really wants to manage disks directly and alone, i.e., no RAID or whatever in between more than a plain stupid HBA, SATA controller or PCIe bus.
Just add more OSDs spread over different hosts, and if you want different racks/rooms and let ceph handle redundancy alone,
it can do so much better (on object level granularity with view of the full cluster and all their disks) than any plain RAID, especially proprietary HW RAID controller, which in my experience aren't really a joy to work with...