Nasan (also known as SAN-FS) is a shared disk file system created by the company DataPlow. It allows 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.
DataPlow has also licensed a version of their file system to be used with Zetera storage products. The Zetera product is licensed on a per hardware enclosure basis and thus can be used by unlimited clients at no additional cost. However, additional enclosures can be expensive due to the proprietary hardware and software. Zetera's version has been modified to operate in a "Storage over IP" configuration. The SoIP configuration uses UDP instead of TCP, thus eliminating the need for TCP offload engines that are used in FC and iSCSI, reducing cost and/or processing overhead. Zetera claims that their file system has the ability to scale in size by joining additional volumes without reformatting (source: Zetera sales rep), and that its speed increases proportionally as additional storage hardware is added (limited only by the network and client computer). Zetera calls their version of the file system Z-SAN.
A limited version of Z-SAN was used in Netgear's Storage Central products starting in 2005. Multiple computers can connect to the Netgear Storage Central at block level using the UDP based SoIP. However, a single volume cannot be shared across a multiple Storage Central enclosures. (source: Netgear phone tech support)
- "Zetera's Z-SAN(TM) technology receives acclaim as it comes to market in NETGEAR(R) product". SAN/LAN Newsletter. September 2005. pp. 11–12.
- "DataPlow Products". Web site. Retrieved May 24, 2013.