Distributed storage array system having plurality of storage devices which each of devices including a modular control unit for exchanging configuration information over a communication link

A distributed storage array system configured to be coupled to a host computer having a host bus, comprising:

• a plurality of modular data storage devices for storing and retrieving data in a selected sequence;
• a communications link;
• and
• a plurality of modular control units, each configured to communicate with the host computer directly over the host bus, each modular control unit being coupled to at least one corresponding data storage device and to each other modular control unit by said communications link, at least one modular control unit includes a receiver for receiving requests from the host computer directly over the host bus for determining a next data storage device of a sequence of data storage devices involved in responding to a pending one of the received requests, and each modular control unit includes:
• a receiver for receiving configuration information from another modular control unit over the communications link;
• and
• a cache for caching one or more transactions handled by said modular control units.

A data storage subsystem couplable to a host computer through a host bus comprising:

• a first modular control unit having a first host bus port couplable to said host bus, said first modular control unit comprising a first storage bus and a communications link;
• a first data storage device coupled to said first storage bus;
• a second modular control unit having a second host bus port couplable to said host bus and to said communications link of said first modular control unit, said second modular control unit comprising a second storage bus;
• and
• a second data storage device coupled to said second storage bus,
• whereby said first and second data storage devices may be configured in conjunction with said first and second modular control units to function as members of a singled RAID set;
• and
• wherein said first modular control unit and said second modular control unit are programmed to exchange information over said communications link between said first modular control unit and said second modular control unit for performance of read/write access of the host computer to the RAID set including a transfer of control in sequence from the first modular control unit to the second modular control unit for transfer of data through the first modular control unit between the first host bus port and the first storage bus and then through the second modular control unit between the second host bus port and the second storage bus.

A data storage subsystem couplable to a host computer through a host bus comprising:

• a first modular control unit having a first host bus port couplable to said host bus, said first modular control unit comprising a first storage bus and a communications link;
• a first data storage device coupled to said first storage bus;
• a second modular control unit having a second host bus port couplable to said host bus and to said communications link of said first modular control unit, said second modular control unit comprising a second storage bus;
• and
• a second data storage device coupled to said second storage bus,
• whereby said first and second data storage devices may be configured in conjunction with said first and second modular control units to function as members of a single RAID set, wherein the first modular control unit and the second modular control unit are programmed for a transfer of control in sequence from the first modular control unit to the second modular control unit for transfer of data through the first modular control unit between the first host bus port and the first storage bus and then through the second modular control unit between the second host bus port and the second storage bus;
• and
• said data storage subsystem further comprising an additional data storage device couplable to said host bus, said additional data storage device being selectively accessible by either of said first and second modular control units by means of said host bus.

A data storage subsystem couplable to a host computer through a host bus comprising:

• a first modular control unit having a first host bus port couplable to said host bus, said first modular control unit comprising a first storage bus and a communications link;
• a first data storage device coupled to said first storage bus;
• a second modular control unit having a second host bus port couplable to said host bus and to said communications link of said first modular control unit, said second modular control unit comprising a second storage bus;
• and
• a second data storage device coupled to said second storage bus,
• whereby said first and second data storage devices may be configured in conjunction with said first and second modular control units to function as members of a single RAID set, wherein the first modular control unit and the second modular control unit are programmed for a transfer of control in sequence between the first modular control unit and the second modular control unit for transfer of data through the first modular control unit between the first host bus port and the first storage bus and through the second modular control unit between the second host bus port and the second storage bus;
• and
• wherein either of said first or said second modular control units may function as a controlling one of said modular control units in response to a command descriptor block received from said host computer.

A computer system comprising:

• a host computer having a host bus for communication of an input/output operation to be performed in conjunction with associated data;
• a plurality of modular control units each having a respective host bus port coupled to said host bus, each of said plurality of modular control units capable of being in communication with others of said plurality of modular units by means of an interconnecting communications link, each of said plurality of modular control units also comprising an associated storage bus;
• and
• a plurality of data storage devices, each of said plurality of data storage devices being coupled to one of said associated storage buses of said plurality of modular control units, at least a subset of said plurality of data storage devices being configurable as members of a single RAID set;
• wherein said first modular control unit and said second modular control unit are programmed to exchange information over said communications link between said first modular control unit and said second modular control unit for performance of read/write access of the host computer to the RAID set including a transfer of control in sequence from the first modular control unit to the second modular control unit for transfer of data through the first modular control unit between the host bus port of the first modular control unit and the first storage bus and then through the second modular control unit between the host bus port of the second modular control unit and the second storage bus.

A computer system comprising:

• a host computer having a host bus for communication of an input/output operation to be performed in conjunction with associated data;
• a plurality of modular control units each having a respective host bus port coupled to said host bus, each of said plurality of modular control units capable of being in communication with others of said plurality of modular units by means of an interconnecting communications link, each of said plurality of modular control units also comprising an associated storage bus;
• a plurality of data storage devices, each of said plurality of data storage devices being coupled to one of said associated storage buses of said plurality of modular control units, at least a subset of said plurality of data storage devices being configurable as members of a single RAID set, the subset of said plurality of data storage devices being coupled to the storage buses of at least a first one of the plurality of modular control units and a second one of plurality of the modular control units, the first one of the plurality of the modular control units and the second one of the plurality of the modular control units being programmed for a transfer of control in sequence from the first one of the modular control units to a second one of the modular control units for transfer of data through the first one of the modular control units between the host bus port of the first one of the modular control units and the storage bus of the first one of the modular control units and then through the second one of the modular control units between the host bus port of the second one of the modular control units and the storage bus of the second one of the modular control units;
• and
• at least one additional storage device couplable to said host bus, said additional data storage device being selectively accessible by any of said plurality of modular control units by means of said host bus.

A computer system comprising:

• a host computer having a host bus for communication of an input/output operation to be performed in conjunction with associated data;
• a plurality of modular control units each having a respective host bus port coupled to said host bus, each of said plurality of modular control units capable of being in communication with others of said plurality of modular units by means of an interconnecting communications link, each of said plurality of modular control units also comprising an associated storage bus;
• and
• a plurality of data storage devices, each of said plurality of data storage devices being coupled to one of said associated storage buses of said plurality of modular control units, at least a subset of said plurality of data storage devices being configurable as members of a single RAID set, the subset of said plurality of data storage devices being coupled to the storage buses of at least a first one of the plurality of modular control units and a second one of the plurality of the modular control units, the first one of the plurality of the modular control units and the second one of the plurality of the modular control units being programmed for a transfer of control in sequence from the first one of the modular control units to a second one of the modular control units for transfer of data through the first one of the modular control units between the host bus port of the first one of the modular control units and the storage bus of the first one of the modular control units and then through the second one of the modular control units between the host bus port of the second one of the modular control units and the storage bus of the second one of the modular control units;
• and
• wherein any of said plurality of modular control units may function as a controlling one of said plurality of modular control units in response to a command descriptor block received from said host computer, said command descriptor block includes a designation or an input/output operation to be performed and data blocks associated with said input/output operation, and said controlling one of said plurality of modular control units communicates a relevant portion of said command descriptor block by means of said communications link to other ones of said plurality of modular control units if at least one of said plurality of data storage devices coupled thereto is to be accessed in conjunction with said input/output operation.