In environments where there is a need for both and is growing fairly quickly, some companies have chosen a NAS gateway which uses the NAS controller (or head) in front of a SAN. Most of the major vendors offer NAS Gateways today (IBM 300G, EMC Celerra, HDS with NetApp, HP E7000, etc.) as well as many independents such as the recent Spinnaker 3300G. The differences between the two technologies are