- A storage area network (SAN) is a dedicated storage network that provides access to consolidated, block level storage. SANs primarily are used to make storage devices (such as disk arrays, tape libraries, and optical jukeboxes) accessible to servers so that the devices appear as locally attached to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the regular network by regular devices. The cost and complexity of SANs dropped in the early 2000s, allowing wider adoption across both enterprise and small to medium sized business environments. A SAN alone does not provide the "file" abstraction, only block-level operations. However, file systems built on top of SANs do provide this abstraction, and are known as SAN filesystems or shared disk file systems.
Red Hat has a pretty comprehensive guide on Linux Storage. Red Hat Storage Configuration Guide