Continuously available computer memory systems

A memory system configurable for attachment to a host computer, comprising:

• a redundant data storage subsystem;
• a spare data storage subsystem;
• first, second and third controller subsystems, each operatively coupled to the redundant data storage subsystem and to the spare data storage subsystem for effecting operations to the storage subsystems;
• and
• first and second power supply subsystems, each coupled to all of the data storage subsystems and the controller subsystems to supply power to the subsystems,
• wherein the controller subsystems are configured such that, upon a failure of one of the three controller subsystems, another one of the three controller subsystems takes control of operations to the three storage systems, and upon a failure of said another one of the three controller subsystems, a remaining one of the three controller subsystems takes control of operations to the three storage subsystems.

A method for operating a memory system for a host computer, wherein the memory system includes redundant data storage subsystems, at least one spare data storage subsystem, and first, second and third controller subsystems, first and second power supply subsystems, the method comprising the steps of:

• a. initially operating the memory system under control of the first controller subsystem;
• b. detecting a failure in the first controller subsystem;
• c. disabling effective communication between the first controller subsystem and the host;
• d. continuing further communication between the host computer and the second controller subsystem, wherein the memory system is operated under the control of the second controller subsystem;
• e. detecting a failure in the second controller subsystem;
• f. disabling effective communication between the second controller subsystem and the host computer;
• and
• g. continuing further communication between the host computer and the third controller subsystem, wherein the memory system is operated under control of the third controller subsystem.

A computer memory system, comprising:

• first, second and third means for storing data;
• first, second and third means for controlling, each operatively coupled to the first, second and third means for storing data, for effecting operations to the means for storing data;
• and
• first and second means for supplying power, each operatively coupled to all of the means for storing data and the means for controlling, wherein the means for controlling are configured such that, upon a failure of one of the means for controlling, another one of the means for controlling will take control of operations to the three means for storing data, and upon a failure of said another one of the three means for controlling, a remaining one of the three means for controlling will take control of operations to the three means for storing data.

A computer memory system, comprising:

• a means for providing redundant data storage;
• a means for providing spare data storage;
• first, second and third means for controlling subsystems, each operatively coupled to the means for providing redundant data storage and to the means for providing spare data storage for effecting operations to the means for providing data storage;
• and
• first and second means for supplying power, each coupled to all of the means for providing data storage and the means for controlling subsystems to supply power to the means for providing data storage and the means for controlling subsystems, wherein upon a failure of one of the three controller subsystems, another one of the three controller subsystems takes control of operations to the three storage systems, and upon a failure of said another one of the three controller subsystems, a remaining one of the three controller subsystems takes control of operations to the three storage subsystems.

A method for implementing a memory system configurable for attachment to a host computer, comprising:

• storing data via first, second and third data storage subsystems;
• effecting operations to the storage subsystems by operatively coupling the first, second and third controller subsystems to the first, second and third data storage subsystems;
• and
• supplying power to the subsystems by operatively coupling first and second power supply subsystems to all of the storage subsystems and the controller subsystems, wherein the controller subsystems are configured such that, upon a failure of one of the three controller subsystems, another one of the three controller subsystems takes control of operations to the three storage systems and upon a failure of said another one of the three controller subsystems, a remaining one of the three controller subsystems takes control of operations to the three storage subsystems.

A computer program product, comprising:

• a computer usable medium having computer code embodied therein for causing implementing a memory system configurable for attachment to a host computer, the computer program product comprising:
• computer readable program code devices configured to cause a computer to effect storing data via first, second and third data storage subsystems;
• computer readable program code devices configured to cause a computer to effect operations to the storage subsystems by operatively coupling the first, second and third controller subsystems to the first, second and third data storage subsystems;
• and
• computer readable program code devices configured to cause a computer to effect supplying power to the subsystems by operatively coupling first and second power supply subsystems to all of the storage subsystems and the controller subsystems, wherein the controller subsystems are configured such that, upon a failure of one of the three controller subsystems, another one of the three controller subsystems takes control of operations to the three storage systems, and upon a failure of said another one of the three controller subsystems, a remaining one of the three controller subsystems takes control of operations to the three storage subsystems.