What is a host storage domain?

From a product standpoint, a host storage domain refers to storage systems that provide heterogeneous server, multi-host tenancy capabilities. Examples of these include Hitachi Data Systems' (HDS) feature on their Lightning 9900V and Thunder 9500V. Different vendors refer to their multi-server shared storage port capability by different names, with various functions supported. Using the HDS example, host storage domains enable multiple host servers running different operating systems to access unique LUNs via a common shared physical storage port on a 9900V or 9500V storage system. HDS host storage domains allow different servers to have access to their own unique LUNs, including accessing what each server thinks is a unique LUN number for example LUN 0 (also known as LUN re-mapping).

To the host server the LUN appears and behaves as though it were on a virtual storage subsystem or array instead...

of being on a shared port. Note that a best practice would still involve LUN or Volume masking from the storage device as well as applicable form of fabric-based zoning for security and isolation. The ability to have multiple servers access multiple LUNs via a shared physical port is not unique; in fact, most all storage subsystems today support some form of shared access beyond simply physically sharing a common storage port via a Fibre Channel switch.