As you can see from the explanations for DAS and NAS, we are talking about storage technologies that are distinguished by their details. So storage area networks (SANs), like DAS and NAS, are a storage technology too. However, unlike DAS and NAS, a SAN is a stand-alone infrastructure. If we refer to the designation, then the SAN is the same as a LAN. While on a LAN there are local computers that comprise a computer network, in a SAN there are storage devices and servers that comprise a storage network. As such, a SAN cannot be accessed by other LAN devices. Just because of that, proprietary protocols or SNMPs provide management for a SAN (see Figure 8.4). Usually, Ethernet or Fibre Channel is used to connect storage to servers.
Figure 8.4. Storage area network (SAN) system