This article provides a description of these two technologies, including their differences. A Storage Area Network connects multiple servers and storage devices on a single network.
SANs also allow sharing the storage infrastructure, without implying data sharing.
This allows higher utilization of storage devices and easier reconfiguration than is possible with direct attached storage. Although sharing of storage devices is possible, it is generally not advisable unless the servers connected to the shared devices are running MS Cluster Server. Precautions must be taken to prevent unintentional access to the storage devices. For switched fabrics, this would involve setting up zones. The technology is based partly on the Virtual Interface Architecture.