Nasan

Nasan (also known as SAN-FS) is a shared disk file system created by DataPlow, that features the ability to give shared, block-level access to a disk volume from multiple client computers without causing file system corruption. DataPlow sells their software directly on a per-seat basis. Each client must purchase the software in order to access a Nasan file system directly. Nasan is made available in Fibre Channel and iSCSI varieties.