A lot of them actually. Ceph personally I've used. But there's a ton, some open source, some paid. Backblaze has a product Buckets or something. Dell powerscale. Cloudian has one. Nutanix has one.
Ceph is awesome for software defined storage where you have multiple storage nodes and multiple storage devices on each. It's way too heavy and resource intensive for a single machine with loopback devices.
Ceph has multiple daemons that would need to be running: monitor, manager, OSD (1 per storage device), and RADOS Gateway (RGW). If you only had a single storage device it would still be 4 daemons.