Most subsystems share the following functional elements:
Controller hardware and logic— Performs most of the storage functions in a subsystem, including the execution of storage commands received from host systems as well as subsystem-based storage applications
External storage network ports— Connects to host systems as well as optional data network ports for management connections
Memory— Used for caching storage data
Internal connection technology (including the bus or network technology)— Used to connect network ports with controllers and memory, as well as the device interconnect technology used to connect storage devices
Storage devices— Where data is eventually stored
Sometimes the term front end is used with storage ...