Continuously available computer memory systems

• US 6,418,539 B1
• Filed: 10/22/1998
• Issued: 07/09/2002
• Est. Priority Date: 05/25/1995
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Walker, Mark S.
• Primary Examiner(s): LE, DIEU MINH T
• Application Number:
  US09/177,232
• Time in Patent Office: 1,356 Days
• Field of Search: 714/5, 714/11, 714/12, 714/13, 711/7, 711/6, 711/5, 711/114, 711/119
• US Class Current: 714/5.1
• CPC Class Codes: G06F 11/20 using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements
• CPC Class Codes: G06F 11/2015 Redundant power supplies power supply failure G06F1/30
• CPC Class Codes: G06F 11/2058 using more than 2 mirrored copies
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups

Abstract

A highly reliable computer memory storage system that is divided into subsystems, each of which is provided in triplicate: a primary subsystem, a backup subsystem and a spare subsystem. Upon detection of a non-recoverable failure in a primary subsystem, the backup subsystem substantially immediately assumes the tasks of the primary subsystem while the spare subsystem is integrated into the operation of the computer memory storage system. The triple replication of all subsystems and mechanisms for detecting failures in at least the primary and secondary subsystems provides an overall memory system which is highly reliable and substantially never requires servicing. In an alternative embodiment, three subsystems can share a load equally, for example a cooling or power supply load requirement. Upon failure, of any one or two of such three redundant subsystems, the remaining subsystems(s) is built with sufficient extra capacity that remaining subsystem(s) can still supply the total power or cooling requirements of the system.

Claims

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

first, second and third data storage subsystems;

first, second and third controller subsystems, each operatively coupled to the first, second and third data storage subsystems for effecting operations to the storage subsystems; and

first and second power supply subsystems, each operatively coupled to all of the 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.

2. The memory system of claim 1, further comprising circuitry, operatively coupled to the first and second power supply subsystems, for altering the operation of at least one of the power supply subsystems to compensate for the failure of another one of the power supply subsystems.

3. The computer memory system of claim 1, wherein the first, second and third data storage subsystems include redundant data storage devices and at least one spare storage device and further wherein the controller subsystems are programmed to cause the at least one spare storage device to assume the storage functions of a redundant data storage device.

4. The computer memory system of claim 1, wherein all of the subsystems are non-serviceable.

5. The computer memory system of claim 1, wherein the data storage subsystems are serviceable and all the other subsystems are non-serviceable.

6. The computer memory system of claim 1, further comprising an electrical isolation device operatively coupled to each controller subsystem and receptive to instructions, wherein upon receipt of an isolation instruction the receiving isolation device electrically isolates the associated controller subsystem from communication with the host computer.

7. The computer memory system of claim 1, wherein the data storage subsystems include magnetic disk drives.

8. The memory system of claim 1, wherein the data storage subsystems include disk drives.

9. The memory system of claim 1, further comprising at least one cooling subsystem disposed to cool the memory system.

10. The memory system of claim 1, wherein the operations include read/write operations.

11. The memory system of claim 1, wherein the operations include read only operations.

12. The memory system of claim 1, wherein the operations include write only operations.

13. 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.

14. The computer memory system of claim 13, wherein the redundant data storage subsystem includes a plurality of storage devices operative as a RAID storage system.

15. The computer memory system of claim 13, wherein the redundant data storage subsystem and the spare data storage subsystem include magnetic disk drives.

16. The memory system of claim 13, comprising circuitry, operatively coupled to the first and second power supply subsystems, for altering the operation of at least one of the power supply subsystems to compensate for the failure of another one of the power supply subsystems.

17. The computer memory system of claim 13, wherein the redundant data storage subsystem and the spare data storage subsystem include redundant data storage devices and at least one spare data storage device and further wherein the controller subsystems are programmed to cause at least one spare data storage device to assume the storage functions of a redundant data storage device.

18. The computer memory system of claim 13, wherein all of the subsystems are non-serviceable.

19. The computer memory system of claim 13, wherein the data storage subsystems are serviceable and all of the other subsystems are non-serviceable.

20. The computer memory system of claim 13, further comprising an electrical isolation device operatively coupled to each controller subsystem and receptive to instructions, wherein upon receipt of an isolation instruction the receiving isolation device electrically isolates the associated controller subsystem from communication with the host computer.

21. The memory system of claim 13, wherein the data storage subsystems include disk drives.

22. The memory system of claim 13, further comprising at least one cooling subsystem disposed to cool the memory system.

23. The memory system of claim 13, wherein the operations include read/write operations.

24. The memory system of claim 13, wherein the operations include read only operations.

25. The memory system of claim 13, wherein the operations include write only operations.

26. 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.

27. The computer memory system of claim 26, wherein all of the subsystems are non-serviceable.

28. The method of claim 26, wherein the data storage subsystems are serviceable and all the other subsystems are non-serviceable.

29. The method of claim 26, wherein the data storage subsystems include magnetic disks.

30. The memory system of claim 26, wherein the data storage subsystems include disk drives.

31. The method of claim 26, further comprising at least one cooling subsystem disposed to cool the memory system.

32. 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.

33. The memory system of claim 32, wherein all of the means for storing data, the means for controlling and the means for supplying power are non-serviceable.

34. The memory system of claim 32, wherein the means for storing data are serviceable and all of the other means for controlling and the means for supplying power are non-serviceable.

35. 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.

36. 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.

37. The method of claim 36, wherein the data storage subsystems include disk drives.

38. The method of claim 36 further comprising the step of cooling the memory system via at least one cooling subsystem.

39. The method of claim 36, wherein the operations include read/write operations.

40. The method of claim 36, wherein the operations include read only operations.

41. The method of claim 36, wherein the operations include write only operations.

42. 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.

43. The computer program product of claim 42, wherein the data storage subsystems include disk drives.

44. The computer program product of claim 42, further comprising computer readable program devices configured to cause cooling the memory system via at least one cooling subsystem.

45. The computer program product of claim 42, wherein the operations include read/write operations.

46. The computer program product of claim 42, wherein the operations include read only operations.

47. The computer program product of claim 42, wherein the operations include write only operations.