Distributed storage array system having a plurality of modular control units

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

• (a) a plurality of data storage means for storing and retrieving data in a selected sequence;
• (b) a communications link independent of said host bus;
• (c) a plurality of modular control units, each configured to communicate with the host computer directly over said host bus, the plurality of modular control units being capable of appearing to the host computer as a single device on said host bus, each modular control unit being coupled to at least one corresponding data storage means and being coupled to each other modular control unit by said communications link, wherein each of said modular control units include:
• (1) means for receiving input/output requests directly from the host computer over said host bus, for mapping each received input/output request onto a sequence of data storage means, and for transferring, over said communications link, responsibility for responding to the received input/output request to the modular control units corresponding to the mapped sequence of data storage means;
• (2) means (a) for receiving from another modular control unit, over said communications link, responsibility for responding to at least a portion of a received input/output request mapped to the data storage means of the receiving modular control unit, and (b) for responding directly to the host computer over said host bus in the mapped sequence of data storage means to the received input/output request.

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

• (a) a communications link independent of said host bus;
• (b) a plurality of nodes, each node including at least one data storage means for storing and retrieving data, being configured to be coupled to said host bus, being addressable by the host computer, and being coupled to the communications link;
• wherein each node includes means for receiving input/output requests from the host computer directly over said host bus, for mapping each received input/output request onto a sequence of nodes, and for transferring, over said communications link, responsibility for responding to the received input/output request to the mapped sequence of nodes;
• and
• wherein each node includes means for receiving from another node, over said communications link, responsibility for responding to a received input/output request mapped to such receiving node, and for responding over said host bus in the mapped sequence to each of the received input/output request.

A method for storing data in a distributed storage array system comprising a plurality of nodes, each node including at least one data storage means for storing and retrieving data, each node being configured to be coupled directly to a host bus of a host computer and addressable by the host computer, and each node being coupled to a communications link independent of said host bus, the plurality of nodes being capable of appearing to the host computer as a single node on said host bus the method including the steps of:

• (a) receiving in a controlling node an input/output request from the host computer directly over said host bus;
• (b) mapping by the controlling node the received input/output request onto a sequence of nodes;
• (c) transferring, over said communications link and by the controlling node, responsibility for responding to the received input/output request to the mapped sequence of nodes;
• (d) receiving in each node in the mapped sequence of nodes, over said communications link, responsibility for responding to the received input/output request mapped to such receiving node;
• and
• (e) responding directly to the host computer over said host bus by each node in the mapped sequence to each such received input/output request.

A receiving modular control unit, configured to be coupled (1) in a distributed storage array system of modular control units to a host computer having a host bus, (2) to at least one corresponding data storage means, and (3) to at least one other modular control unit in the distributed storage array system by means of a communications link, comprising:

• (a) means for receiving input/output requests from the host computer directly over said host bus, for determining a sequence of data storage means involved in responding to a pending one of the input/output requests, and for transferring, over said communications link, responsibility for responding to the pending one of such input/output requests to the modular control units corresponding to the sequence of involved data storage means;
• and
• (b) means for receiving from another modular control unit in the distributed array of modular control units, over said communications link, responsibility for responding to a received input/output request involving the receiving modular control unit, and for responding directly to the host computer over said host bus in the determined sequence to the received input/output request,
• wherein all the modular control units can directly communicate with the host computer over said host bus, and the plurality of modular control units are capable of appearing to the host computer as a single device on said host bus.