Direct-attached storage (DAS) refers to a digital storage system directly attached to a server or workstation, without a storage network in between. It is a retronym, mainly used to differentiate non-networked storage from SAN and NAS.
A DAS device can be shared between multiple computers, if only it provides multiple interfaces (ports) that allow concurrent and direct access. This way it can be usable for computer clusters. In fact, most SAN-attachable storage devices or NAS devices can be easily used as DAS devices - all that is needed is to disconnect their ports from the data network and connect one or more ports directly to a computer (with a plain one-to-one cable).