Disk array system

• US 5,274,645 A
• Filed: 04/23/1992
• Issued: 12/28/1993
• Est. Priority Date: 03/02/1990
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: Micron Technology, Inc.
• Inventors: Gajjar, Kumar, Glider, Joseph S., Henson, Larry P., Jaffe, David H., Koontz, Robert S., Idleman, Thomas E., Powers, David T.
• Primary Examiner(s): ATKINSON, CHARLES
• Application Number:
  US07/872,560
• Time in Patent Office: 614 Days
• Field of Search: 371/10.1, 371/10.2, 371/11.1, 371/40.1, 395/575
• US Class Current: 714/6.1
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1666 where the redundant component is memory or memory area
• 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 11/201 between storage system components
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence

Abstract

A method and apparatus for controlling data flow between a computer and a group of memory devices arranged in a particular logical configuration. The system includes a group of first level controllers and a group of second level controllers. The first level controllers and the second level controllers work together such that if one of the second level controllers fails, the routing between the first level controllers and the memory devices is switched to a properly functioning second level controller without the need to involve the computer in the rerouting process. The logical configuration of the memory devices remains constant. The invention also includes switching circuitry which permits a functioning second level controller to assume control of a group of memory devices formerly primarily controlled by the failed second level controller. In addition, the invention provides error check and correction as well as mass storage device configuration circuitry.

Claims

1. A system for storing data received from an external source, comprising:

at least two control means for providing control of data flow to and from the external source;

a plurality of storage means coupled to said at least two control means wherein said storage means are divided into groups and each group is controlled by said at least two of said control means such that in the case that a first control means coupled to a particular group of storage means fails, control of said particular group is assumed by a second control means;

a plurality of data handling means coupled to said at least two control means for disassembling data into data blocks to be written across a group of said storage means; and

error detection means coupled to said control means and said storage means for calculating at least one error detection term for each group of storage means based on the data received from the external source using a selected error code and providing said error detection term to be compared with data to detect errors, said error detection means being coupled to each of said control means to receive the data from said control means and transmit said error detection term to an error code storage means in said group of storage means.

2. The system of claim 1 wherein said data handling means further include assembly means for assembling said data blocks received from said control means.

3. The system of claim 1 further comprising a first bus for coupling to said external source and a plurality of buffer means coupled to said first bus and to said control means for buffering data received by and transmitted from the system.

4. The system of claim 3 further comprising error correction means coupled to said error detection means for correcting error in data as said data is transmitted from either said buffer means to said storage means through said data handling means or from said storage means to said buffer means through said data handling means.

5. The system of claim 3 wherein the error detection means uses a Reed-Solomon error code to detect errors in said data received from said buffer means and said storage means.

6. The system of claim 3 wherein said data handling means includes detachment means coupled to said error detection means for detaching from the system storage means and buffer means which transmit erroneous data responsive to receiving said error detection term from said error detection means.

7. The system of claim 1 wherein said plurality of storage means comprises:

a first group of data storage means for storing data from the external source; and

a second group of error check and correction (ECC) storage means for storing ECC data generated by said error detection means.

8. The system of claim 1 wherein each of said plurality of storage means stores data and error check and correction (ECC) data in a predefined pattern.

9. In a system including at least two control means for communicating with an external source and a plurality of storage means wherein at least two of the control means are connected to each of the storage means, a method for storing data received from the external source comprising the steps of:

receiving data from the external source;

configuring the plurality of storage means into groups wherein each group is initially controlled by at least two of the control means such that in the case that one of the control means fails, the storage means of each group is accessible through another one of the control means;

disassembling data into groups of data blocks to be written to said plurality of storage means;

calculating at least one error detection term from said data using a selected error code;

storing said data blocks in a first of said groups of storage means; and

storing said at least one error detection term in said first of said groups of storage means.

10. The method of claim 9 further comprising the steps of:

retrieving said data blocks from said first of said groups of storage means;

calculating a check error detection term from said data blocks using a selected error code;

retrieving said at least one error detection term from said first of said groups of storage means; and

comparing said check error detection term to said at least one error detection term to determine that said data has not been corrupted.

11. The method of claim 10 further comprising the step of correcting said data if it is determined that said data has been corrupted.

12. The method of claim 10 further comprising the step of assembling said data blocks into a form in which it was received from the external source.

13. The method of claim 9 wherein the step of configuring further comprises the step of setting a plurality of switching means to allow said data blocks to be passed between the control means and the storage means in a predefined pattern.

14. The method of claim 9 further comprising the step of detaching a particular storage means upon which said data was stored if it is determined that said data has been corrupted.

15. A system for storing data received from an external source, comprising:

control means for providing control of data flow to and from the external source;

a plurality of storage means coupled to said control means wherein said storage means are divided into groups;

a plurality of data handling means coupled to said control means for disassembling data with data blocks to be written to said storage means; and

error detection means coupled to said control means for receiving said data blocks in parallel form and detecting errors in each data block substantially simultaneously as said data blocks are written to said storage means.

16. The system of claim 15 further comprising data correction means coupled to said error detection means for correcting corrupted data in response to an error detection signal provided by said error detection means.

17. The system of claim 16 wherein said plurality of storage means comprises:

a first group of data storage means for storing data from the external source; and

a second group of error check and correction (ECC) storage means for storing ECC data generated by said error correction means.

18. The system of claim 16 wherein the error detection means uses a Reed-Solomon error code to detect errors in said data received from said buffer means and said storage means.

19. The system of claim 16 wherein the error correction means uses a Reed-Solomon error code to correct errors in said data received from said buffer means and said storage means.

20. The system of claim 15 further comprising detachment means coupled to said error detection means for detaching a particular storage means from the system which has provided corrupted data as determined by said error detection means.

21. The system of claim 15 wherein said data handling means further includes assembly means for assembling said data blocks received from said control means.

22. The system of claim 15 further comprising a first bus for coupling to said external source and a plurality of buffer means coupled to said first bus and to said control means for buffering data received by and transmitted from the system.

23. The system of claim 15 wherein each of said plurality of storage means stores data and error check and correction (ECC) data in a predefined pattern.

24. In a system including control means for communicating with an external source and a plurality of storage means, a method for storing data received from the external source comprising the steps of:

receiving data from the external house;

disassembling the data into groups of data blocks to be written to said plurality of storage means;

calculating at least one error detection term for each data block substantially simultaneously; and

storing said data blocks and said at least one error detection term in a first of said groups of storage means substantially simultaneously.

25. The method of claim 24 further comprising the steps of:

retrieving said data blocks from said first of said groups of storage means;

calculating a check error detection term from said data blocks using a selected error code;

retrieving said at least one error detection term from said first of said groups of storage means; and

comparing said check error detection term to said at least one error detection term to determine that said data has been not corrupted.

26. The method of claim 25 further comprising the step of correcting said data if it is determined that said data has been corrupted.

27. The method of claim 25 further comprising the step of assembling said data blocks into a form in which it was received from the external source.

28. The method of claim 24 wherein the step of configuring further comprises the step of setting a plurality of switching means to allow said data blocks to be passed between the control means and the storage means in a predefined pattern.

29. The method of claim 24 further comprising the step of detaching a particular storage means upon which said data was stored if it is determined that said data has been corrupted.