Three interconnected raid disk controller data processing system architecture

• US 6,330,642 B1
• Filed: 06/29/2000
• Issued: 12/11/2001
• Est. Priority Date: 06/29/2000
• Status: Expired due to Fees

• Current Assignee: Bull HN Information Systems Incorporated (Atos SE)
• Original Assignee: Bull HN Information Systems Incorporated (Atos SE)
• Inventors: Carteau, Daniel
• Primary Examiner(s): Kim, Matthew
• Assistant Examiner(s): ELMORE, STEPHEN C
• Application Number:
  US09/607,028
• Time in Patent Office: 530 Days
• Field of Search: 711/114, 711/119, 711/161, 711/162
• US Class Current: 711/114
• CPC Class Codes: G06F 11/201 between storage system components
• CPC Class Codes: G06F 11/2092 Techniques of failing over between control units
• CPC Class Codes: G06F 2201/85 Active fault masking without idle spares active fault masking without idle spare hardware where processing functionality is redundant G06F11/2035

Abstract

A data processing system with a RAID cache disk subsystem utilizes three RAID cache disk controllers to provide increased performance along with increased reliability, especially in the event of a failure of one of the disk controllers. Disk writes are mirrored in two disk controllers in order to guarantee integrity in the event of a disk controller or interface failure. Typically this write caching must be terminated when one of the controllers fails in order to maintain integrity. In the present invention, write caching continues utilizing the two remaining disk controllers.

Claims

1. A disk subsystem for use in a data processing system wherein the disk subsystem comprises:

a first disk controller comprising;

a first disk controller write cache; and

a first means for coupling the first disk controller to a first host computer;

a second disk controller bidirectionally coupled to the first disk controller and comprising;

a second disk controller write cache,

a first means for coupling the second disk controller to the first host computer;

a third disk controller comprising;

a third disk controller write cache,

a first means for coupling the third disk controller to the first host computer;

a set of disk drives logically comprising;

a first set of logical disk drives and a third set of logical disk drives bidirectionally coupled to the first disk controller and the second disk controller;

a fourth set of logical disk drives and a sixth set of logical disk drives bidirectionally coupled to the second disk controller and the third disk controller; and

a second set of logical disk drives and a fifth set of logical disk drives bidirectionally coupled to the third disk controller and the first disk controller; and

means for bidirectionally coupling the first disk controller to the second disk controller, the second disk controller to the third disk controller, and the third disk controller to the first disk controller;

wherein;

when in a first state which requires that the first disk controller, the second disk controller, and the third disk controller be active and able to communicate with the first host computer;

the first disk controller provides write access to, write caching of, and delayed writing to the first set of logical disk drives and the second set of logical disk drives and provides write cache mirroring of the third set of logical disk drives and the fifth set of logical disk drives;

the second disk controller provides write access to, write caching of, and delayed writing to the third set of logical disk drives and the fourth set of logical disk drives and provides write cache mirroring of the first set of logical disk drives and the sixth set of logical disk drives; and

the third disk controller provides write access to, write caching of, and delayed writing to the fifth set of logical disk drives and the sixth set of logical disk drives and provides write cache mirroring of the second set of logical disk drives and the fourth set of logical disk drives.

2. The disk subsystem in claim 1 wherein:

the first means for coupling the first disk controller to the first host computer is a channel connection.

3. The disk subsystem in claim 2 wherein:

the channel connection is a serial interface.

4. The disk subsystem in claim 2 wherein:

the channel connection is a SCSI interface.

5. The disk subsystem in claim 1 wherein:

the first means for coupling the first disk controller to the first host computer includes a storage area network (SAN).

6. The disk subsystem in claim 1 wherein:

the means for bidirectionally coupling the first disk controller to the second disk controller, the second disk controller to the third disk controller, and the third disk controller to the first disk controller comprises;

a direct connection between the first disk controller and the second disk controller;

a direct connection between the second disk controller and the third disk controller; and

a direct connection between the third disk controller and the first disk controller.

7. The disk subsystem in claim 1 wherein:

the first set of logical disk drives and the third set of logical disk drives bidirectionally coupled to the first disk controller and the second disk controller with a SCSI channel; and

the means for bidirectionally coupling the first disk controller to the second disk controller comprises;

a SCSI connection between the second disk controller and the first disk controller.

8. The disk subsystem in claim 1 wherein:

the first disk controller further comprises;

a first means for coupling the first disk controller to a second host computer.

9. The disk subsystem in claim 1 wherein:

the first disk controller further comprises;

a second means for coupling the first disk controller to the first host computer.

10. The disk subsystem in claim 9 wherein:

the first disk controller further comprises;

a first means for coupling the first disk controller to a second host computer; and

a second means for coupling the first disk controller to the second host computer.

11. The disk subsystem in claim 1 wherein:

when in a second state which requires that the first disk controller and the second disk controller be active and able to communicate with the first host computer and the third disk controller be unable to communicate with the first host computer;

the first disk controller provides write access to, write caching of, and delayed writing to the first set of logical disk drives and provides write cache mirroring of the third set of logical disk drives;

the second disk controller provides write access to, write caching of, and delayed writing to the third set of logical disk drives and provides write cache mirroring of the first set of logical disk drives and the sixth set of logical disk drives;

the first disk controller provides write access to the second set of logical disk drives and the fifth set of logical disk drives; and

the first second controller provides write access to the fourth set of logical disk drives and the sixth set of logical disk drives.

12. The disk subsystem in claim 11 wherein:

when in a third state which requires that the first disk controller be active and able to communicate with the first host computer and the third disk controller and the second disk controller be unable to communicate with the first host computer;

the first disk controller provides write access to the first set of logical disk drives, the second set of logical disk drives, the third set of logical disk drives, and the fifth set of logical disk drives.

13. The disk subsystem in claim 11 wherein:

the fourth set of logical disk drives and the sixth set of logical disk drives are bidirectionally coupled to the first disk controller;

the second set of logical disk drives and the fifth set of logical disk drives are bidirectionally coupled to the second disk controller; and

when in the second state;

the first disk controller provides write access to, write caching of, and delayed writing to the second set of logical disk drives and the fifth set of logical disk drives and provides write cache mirroring of the fourth set of logical disk drives and the sixth set of logical disk drives; and

the second disk controller provides write access to, write caching of, and delayed writing to the fourth set of logical disk drives and the sixth set of logical disk drives and provides write cache mirroring of the second set of logical disk drives and the fifth set of logical disk drives.

14. The disk subsystem in claim 13 wherein:

when in a third state which requires that the first disk controller be active and able to communicate with the first host computer and the third disk controller and the second disk controller be unable to communicate with the first host computer;

the first disk controller provides write access to the first set of logical disk drives, the second set of logical disk drives, the third set of logical disk drives, the fourth set of logical disk drives, the fifth set of logical disk drives, and the sixth set of logical disk drives.

15. The disk subsystem in claim 1 wherein:

the first disk controller is a RAID cache disk controller.

16. The disk subsystem in claim 15 wherein:

the first disk controller further comprises;

a first disk controller read cache; and

the first disk controller write cache and the first disk controller read cache together form a first disk controller cache memory.

17. The disk subsystem in claim 16 wherein:

a size of the first disk controller cache memory allocated to the first disk controller write cache is dynamic.

18. The disk subsystem in claim 16 wherein:

a size of the first disk controller cache memory allocated to the first disk controller write cache is static.

19. The disk subsystem in claim 1 wherein:

when in the first state;

the first disk controller further provides write cache mirroring of the fourth set of logical disk drives and the sixth set of logical disk drives;

the second disk controller further provides write cache mirroring of the second set of logical disk drives and the fifth set of logical disk drives; and

the third disk controller further provides write cache mirroring of the first set of logical disk drives and the third set of logical disk drives.

20. A data processing system comprising:

a first host computer;

a first disk controller comprising;

a first disk controller write cache; and

a first means for coupling the first disk controller to the first host computer;

a second disk controller bidirectionally coupled to the first disk controller and comprising;

a second disk controller write cache,

a first means for coupling the second disk controller to the first host computer;

a third disk controller comprising;

a third disk controller write cache,

a first means for coupling the third disk controller to the first host computer;

a set of disk drives logically comprising;

a first set of logical disk drives and a third set of logical disk drives bidirectionally coupled to the first disk controller and the second disk controller;

a fourth set of logical disk drives and a sixth set of logical disk drives bidirectionally coupled to the second disk controller and the third disk controller; and

a second set of logical disk drives and a fifth set of logical disk drives bidirectionally coupled to the third disk controller and the first disk controller; and

means for bidirectionally coupling the first disk controller to the second disk controller, the second disk controller to the third disk controller, and the third disk controller to the first disk controller;

wherein;

when in a first state which requires that the first disk controller, the second disk controller, and the third disk controller be active and able to communicate with the first host computer;

the first disk controller provides write access to, write caching of, and delayed writing to the first set of logical disk drives and the second set of logical disk drives and provides write cache mirroring of the third set of logical disk drives and the fifth set of logical disk drives;

the second disk controller provides write access to, write caching of, and delayed writing to the third set of logical disk drives and the fourth set of logical disk drives and provides write cache mirroring of the first set of logical disk drives and the sixth set of logical disk drives; and

the third disk controller provides write access to, write caching of, and delayed writing to the fifth set of logical disk drives and the sixth set of logical disk drives and provides write cache mirroring of the second set of logical disk drives and the fourth set of logical disk drives.