Arrayed disk drive system and method

• US 5,148,432 A
• Filed: 09/03/1991
• Issued: 09/15/1992
• Est. Priority Date: 11/14/1988
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: Array Technology Corp. (Dell Technologies Inc.)
• Inventors: Warner, David M., Hubis, Walter A., Brant, William A., Stallmo, David C., Gordon, David W.
• Primary Examiner(s): ATKINSON, CHARLES
• Application Number:
  US07/758,393
• Time in Patent Office: 378 Days
• Field of Search: 371/10.1, 371/10.2, 371/11.1, 364/243.1, 364/248.1, 364/268.5, 364/944, 364/952.1, 364/964.7, 395/575
• US Class Current: 714/6.32
• CPC Class Codes: G06F 11/08 Error detection or correction by redundancy in data representation, e.g. by using checking codes
• CPC Class Codes: G06F 11/1096 Parity calculation or recalculation after configuration or reconfiguration of the system
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0673 Single storage device
• CPC Class Codes: G11B 20/1252 for discontinuous data, e.g. digital information signals, computer programme data
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: H03M 13/00 Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes error detection or error correction for analogue/digital, digital/analogue or code conversion H03M1/00 – H03M11/00; specially adapted for digital computers G06F11/08; for information storage based on relative movement between record carrier and transducer G11B, e.g. G11B20/18; for static stores G11C

Abstract

An arrayed disk drive system for providing memory to a computer, said arrayed system having a plurality of disk drives configured to form an array, said arrayed disk drives accessed by a plurality of channels, each channel accessing a plurality of disk drives, including a means for controlling the logical configuration of the arrayed disk drives to appear to the computer as any conceivable arrangement of disk drives, whereby the arrayed disk drive may appear to the computer as the plurality of disk drives, or as one large disk drive comprised of all the arrayed disk drives, or any combination in between. A means for providing a plurality of levels of redundancy on data read or written by the computer to the arrayed disk drives is provided, as well as means controlled by the controlling means for enabling from none to the plurality of levels of redundancy to operate on data being read or written from the arrayed disk drives.

Claims

1. An arrayed disk drive system for providing memory to a computer comprising:

a plurality of disk drives configured to form an array, said arrayed disk drives coupled to a plurality of channels, each channel accessing a plurality of disk drives, and each of the arrayed disk drives having a plurality of sectors;

disk controlling means, coupled to communicate with the channels, (a) for grouping the disk drives to define one or more logical groups each of which appears to the computer as a single disk drive so that the arrayed disk drives appear to the computer as any conceivable arrangement of disk drives, whereby the arrayed disk drive may appear to the computer as the plurality of disk drives, or as one large disk drive comprised of all the arrayed disk drives, or any combination in between, and (b) for controlling the transfer of data between the computer and the disk drives in accordance with the grouping;

means for providing a plurality of levels of data loss protection on data read or written by the computer to the arrayed disk drives; and

means controlled by the disk controlling means for selectively enabling from none to the plurality of levels of data loss protection to operate on data being read or written from the arrayed disk drives.

2. The arrayed disk drive system of claim 1 further including a buffer memory coupled to the disk controlling means, wherein the disk controlling means further comprises:

means for initially transmitting data received from the computer to the buffer memory and dividing the data into a predetermined number of blocks, each block being equal in quantity size to a sector; and

striping means for providing said blocks sequentially from one channel to another for storage in the disk drives.

3. The arrayed disk drive system of claim 2 having a common data bus connecting to the plurality of channels wherein the means for providing data loss protection further comprises:

means for performing data loss protection processing as the data propagates along the data bus from or to a channel during a computer read or write operation, wherein provision of data loss protection requires no more additional time than that necessary to complete the read or write operation.

4. The arrayed disk drive system of claim 3 wherein the disk controlling means further comprises:

means for mapping virtual memory locations specified by the computer in a read or write request to the arrayed disk drives, said arrayed disk drives being physical memory locations.

5. The arrayed disk drive system of claim 4 further comprising means for implementing data loss protection when a disk drive from the arrayed disk drives is removed for installing a replacement disk drive so as to provide data corresponding to data in the removed disk drive, whereby replacement of a disk drive is transparent to the computer and no down time is experienced by the computer.

6. The arrayed disk drive system of claim 5 wherein the means for implementing further comprises means for regenerating data for said removed disk drive based upon data contained in other disk drives when data loss protection is provided by said disk controlling means.

7. The arrayed disk drive system of claim 5 further comprising:

a plurality of spare disk drives; and

means for configuring any of said spares to be logically identical to a defective or removed disk drive, whereby a spare takes the logical place of a defective or removed disk drive such that data for the defective or removed disk drive is written to the spare disk drive, and data to be read from the defective or removed disk drive is read from the spare drive.

8. The arrayed disk drive system of claim 7 further comprising means for recreating the data of a defective or removed disk drive when data loss protection is provided and storing the recreated data on a spare configured by said spare configuring means.

9. The arrayed disk drive system of claim 8 wherein the disk controlling means further comprises a plurality of process means, said plurality of process means comprising:

a computer interrupt process means for servicing interrupts from and to said computer and functioning as an interface between said computer and said plurality of process means;

a plurality of computer task process means for honoring read and write requests from the computer to and from the arrayed disk drives, whereby the plurality of computer task process means controls writes from the computer to the arrayed disk drives and reads from the arrayed disk drives to the computer, said plurality of computer task process means also enabling said levels of data los protection;

a plurality of channel task process means for initiating the arrayed disk drives to receive write data from the plurality of computer task process means and to initiate the plurality of computer task process means to receive read data from the arrayed disk drives;

a plurality of channel controlling process means for controlling the movement of data from the plurality of computer task process means to each of the plurality of channels during a read, and from each of the plurality of channels to the plurality of computer task process means during a write; and

a plurality of channel interrupt process means for processing interrupts to and from each of the plurality of channels.

10. The arrayed disk drive system of claim 9 further comprising an operating system, said plurality of process means being connected to one another by said operating system and functioning thereon, whereby said disk controlling means operates on said operating system.

11. The arrayed disk drive system of claim 10, having input output parameter blocks from said computer, further comprising:

means for queuing said input output parameter blocks, said queuing means operating when there are more input output parameter blocks than the plurality of computer task process means.

12. The arrayed disk drive system of claim 11 wherein the disk controlling means further comprises:

means for providing a priority to each requests from the computer, each of said plurality of process means seeing said priority.

13. The arrayed disk drive system of claim 12 having a processor on which said operating system and said disk controlling means operate, said disk controlling means being comprised of high level computer software, said operating system and said high level computer software combine to make said disk controlling means retargetable on a plurality of processors.

14. The arrayed disk drive system of claim 13 further comprising a means for defining the location of each of the plurality of disk drives in the arrayed disk drives;

and

means for communicating attempts to place a disk drive in a location other than its defined location.

15. The arrayed disk drive system of claim 14 having a customer engineering means said arrayed disk drive system further comprising a plurality of processors, each of said plurality of channels comprising a processor, said disk controlling means comprising a processor, and said customer engineering means having a plurality of processors, wherein said disk controlling means further comprises means for providing simultaneous operation of said plurality of processors, whereby said arrayed disk system is capable of parallel processing and being configured to provide high bandwidth or high transaction rate processing or any compromise therebetween.

16. An arrayed memory system for providing memory to a host computer, comprising:

a plurality of storage devices configured to form an array, said arrayed storage devices accessed by a plurality of channels, each channel accessing a plurality of storage devices, and;

controlling means separate from the host computer for configuring said plurality of storage devices to appear to the host computer as any arrangement of storage devices, whereby the plurality of storage devices may be configured to appear all as one logical storage device, or as plural logical storage devices equal to the plurality of storage devices, or any configuration therebetween.

17. The arrayed memory system of claim 16 wherein the controlling means further comprises:

means for providing a plurality of levels of data loss protection on data read or written by the computer to the arrayed storage devices; and

means controlled by the controlling means for enabling from none to the plurality of levels of data loss protection to operate on data being read or written from the arrayed storage devices.

18. The arrayed disk drive system of claim 17 wherein the disk controlling means further comprises a plurality of process means, said plurality of process means comprising:

a computer interrupt process means for servicing interrupts from and to said computer and functioning as an interface between said computer and said plurality of process means;

a plurality of computer task process means for honoring read and write requests from the computer to and from the arrayed disk drives, whereby the plurality of computer task process means controls reads from the computer to the arrayed disk drives and writes from the arrayed disk drives to the computer, said plurality of computer task process means also enabling said levels of redundancy;

a plurality of channel task process means for initiating the arrayed disk drives to receive read data from the plurality of computer task process means and to initiate the plurality of computer task process means to receive write data from the arrayed disk drives;

a plurality of channel controlling process means for controlling the movement of data from the plurality of computer task process means to each of the plurality of channels during a read, and from each of the plurality of channels to the plurality of computer task process means during a write; and

a plurality of channel interrupt process means for processing interrupts to and from each of the plurality of channels.

19. A method for providing memory to a host computer employing an arrayed system having a plurality of storage devices configured to form an array, said arrayed storage devices accessed by a plurality of channels, each channel accessing a plurality of storage devices, comprising the steps of:

logically grouping the arrayed storage devices to form logical storage devices which appear to the host computer as any conceivable arrangement of storage devices, whereby the arrayed storage devices may appear to the host computer as the plurality of storage devices, or as one large storage device comprised of all the arrayed storage devices, or any combination in between;

providing a plurality of levels of data loss protection on data read or written by the computer to the arrayed storage devices;

selectively enabling from none to the plurality of levels of data loss protection to operate on data being read or written from the arrayed storage devices.

20. The method of claim 19 wherein the arrayed system has a common data bus connecting to the plurality of channels and wherein the step of providing data loss protection further comprises the step of:

performing data loss protection processing as the data propagates along the data bus from or to a channel during a host computer read or write operation, whereby data loss protection requires no more additional time than that necessary to complete the read or write operation.

21. The method of claim 20 wherein the logical grouping step further comprises the step of:

mapping virtual memory locations designated by the host computer to the arrayed storage devices, said arrayed storage devices being physical memory locations.

22. The method of claim 21 further comprising the step of performing data loss protection processing to provide continuous operation of the arrayed memory system when a storage device from the arrayed storage devices is removed for installing a replacement disk drive, whereby no down time is experienced by the computer.

23. The method of claim 22 wherein the continuous operation providing step further comprises the step of regenerating data for said removed storage device by way of data loss protection processing.

24. The method of claim 22 further comprising the steps of:

providing a plurality of spare storage devices; and

configuring said spares to be logically identical to a defective or removed storage device, whereby a spare takes the logical place of a defective or removed storage device such that data for the defective or removed storage device is written to the spare storage device, and data to be read from the defective or removed storage device is read from the spare storage device.

25. The method of claim 24 further comprising the step of providing a plurality of process means, said plurality of process means comprising the steps of:

providing a computer interrupt process means for servicing interrupts from and to said computer and functioning as an interface between said computer and said plurality of process means;

providing a plurality of computer task process means for honoring read and write requests from the computer to and from the arrayed storage devices, whereby the plurality of computer task process means controls reads from the computer to the arrayed storage devices and writes from the arrayed storage devices to the computer, said plurality of computer task process means also enabling said levels of redundancy;

providing a plurality of channel task process means for initiating the arrayed storage devices to receive read data from the plurality of computer task process means and to initiate the plurality of computer task process means to receive write data from the arrayed storage devices;

providing a plurality of channel controlling process means for controlling the movement of data from the plurality of computer task process means to each of the plurality of channels during a read, and from each of the plurality of channels to the plurality of computer task process means during a write; and

providing a plurality of channel interrupt process means for processing interrupts to and from each of the plurality of channels.

26. The method of claim 25 further comprising the step of providing an operating system, said plurality of process means being connected to one another by said operating system and functioning thereon.

27. The method of claim 26, having input output parameter blocks from said computer, further comprising the steps of:

providing queuing means for queuing said input output parameter blocks, said queuing means operating when there are more input output parameter blocks than the plurality of computer task process means.

28. The method of claim 27 wherein the step of controlling movement of data further comprises the step of:

providing a priority to each request from the computer, each of said plurality of process means seeing said priority.

29. A configurable arrayed disk drive system for providing memory to a host computer, comprising:

a plurality of disk drives; and

array control means for selectively defining any combination of one or more logical groups of disk drives in which each group includes at least one disk drive and in which the combination employs up to the plurality of disk drives, and for selectively assigning disk drives from among the plurality to form the logical groups, the array control means including (a) disk drive control processing means coupled to the disk drives to control read/write operations of each disk drive, and (b) system control processing means, coupled to the disk drive control processing means, for receiving read/write requests for any logical group form the host computer and controlling the disk drive control processing means to cause appropriate read/write operations to occur with respect to each disk drive in the logical group for which the request was received, wherein each logical group is accessed by the host computer as if it were a separate single disk drive.

30. A disk drive system as in claim 29 further including data loss protection means for generating parity information for enabling reconstruction of data lost from a disk drive, the parity information being generated based upon data from a parity group which includes two or more disk drives;

and

wherein the system control processing means selectively enables the data loss protection means for each logical group to provide data loss protection therefor.

31. A disk drive system as in claim 30 wherein the data loss protection means includes means for generating protection data in accordance with a first protection scheme and a second protection scheme, and wherein the system control processing means can selectively enable one or more protection schemes for each logical group.

32. A disk drive system as in claim 30 wherein any logical group of disk drives for which the data loss protection means is enabled includes a plurality of disk drives and the disk drives contained in the logical group store both data from the host computer and protection data generated by the data loss protection means.

33. A disk drive system as in claim 29 further including means for maintaining any disk drive which is not part of a defined logical group as a spare which can be substituted into any logical group to replace a disk drive in the group.

50. A disk drive system as in claim 29 wherein the array control means includes a common data bus coupled to the system control processing means and the disk drive control processing means for providing communication therebetween.

51. A disk drive system as in claim 50 wherein there are a plurality of disk drive channels, each having at least one disk drive, and wherein the disk drive control processing means is comprised of a plurality of channel processing means provided separately for each disk drive channel.

34. A configurable arrayed disk drive system for providing memory to a host computer, comprising:

a plurality of disk drives;

a common bus for transmitting data to and from each of the disk drives;

array control means for selectively configuring at least some of the disk drives into one or more logical groups of at least one disk drive each, for dividing data received from the host computer to be stored in any particular group into designated portions and for providing the designated portions to the common data bus; and

controller means coupled between the common data bus and the disk drives, for recognizing and transmitting each designated portion of data to a particular disk drive for storage.

35. A disk drive system as in claim 34 further including a plurality of channel buses coupled to the common bus, wherein the controller means includes a plurality of channel controllers, one coupled to each channel bus for controlling the transmission of data on the channel buses, and wherein there is at least one disk drive coupled to each channel bus.

36. A disk drive system as in claim 35 wherein there are a plurality of disk drives coupled to each channel bus.

37. A disk drive system as in claim 36 wherein the controller means further includes a plurality of disk drive controllers, one associated with each disk drive, for controlling the transmission of data to each disk drive.

38. A disk drive system as in claim 34 further including data loss protection means, coupled to the common bus, for generating reconstruction data for enabling reconstruction of data lost from a disk drive and wherein the array control means can selectively configure disk drives into at least one data reconstruction group and selectively enable operation of the data loss protection means for each data reconstruction group, wherein each data reconstruction group stores data from the computer and reconstruction data.

39. A disk drive system as in claim 38 wherein each data reconstruction group is formed of a logical group.

40. A disk drive system as in claim 38 wherein the data loss protection means includes first means and second means for generating first reconstruction data and second reconstruction data, respectively, wherein the array control means can selectively enable either one or both of the first and second means with respect to any data reconstruction group.

41. A disk drive system as in claim 38 wherein the array control means can configure the logical groups and data reconstruction groups to include less than all of the disk drives and to maintain disk drives which are not in a logical group as a group of spares which may be substituted into any logical group to replace a failed disk drive.

42. A disk drive system as in claim 37 further including data loss protection means, coupled to the common bus, for generating reconstruction data for enabling reconstruction of data lost from a disk drive and wherein the array control means can selectively configure disk drives into at least one data reconstruction group and selectively enable operation of the data loss protection means for each data reconstruction group, wherein each data reconstruction group stores data from the computer and reconstruction data.

43. A disk drive system as in claim 42 wherein the array control means can configure the disk drives to maintain at least one disk drive outside of any logical group to function as a spare which may be selectively switched into any logical group to replace a failed disk drive.

44. A disk drive system as in claim 43 wherein the array control means configures all disk drives coupled to a particular channel bus as spares.

52. A disk drive system as in claim 34 wherein data from the host computer is written to the disk drive system and data stored in the disk drive system is read to the host computer and wherein the host computer provides a read/write request for any logical group as if the logical group were a single physical disk drive when a read/write operation is desired, wherein:

the array control means includes system control processing means for receiving and analyzing read/write requests from the host computer to determine which disk drives any particular read/write request pertains to and for controlling the controller means to cause reading from or writing to the appropriate disk drives in order to execute the request.

53. A disk drive system as in claim 52 including means for coupling the host computer to the common bus, wherein read/write requests and data are transmitted on the common bus.

54. A disk drive system as in claim 52 wherein the array control means includes a memory means for receiving and temporarily storing data from the host computer for subsequent division into designated portions to be transferred to the disk drives and for receiving and temporarily storing designated portions from the disk drives for subsequent grouping into data to be transferred to the host computer as a single group, wherein the system control processing means controls the division into designated portions and grouping of designated portions.

55. A disk drive system as in claim 34 wherein the array control means includes means for retrieving related designated portions of data which were previously stored in the disk drives, combining the designated portions of data into a group and providing the combined data to the common bus for transfer to the host computer.

45. A configurable arrayed disk drive system for providing memory to a computer, comprising:

a common bus for receiving data from the computer and transmitting data to the computer;

a plurality of channel buses coupled to the common bus;

a plurality of channel controllers, one coupled to each channel bus, for controlling the transfer of data between the common bus and the channel buses;

a plurality of disk controllers, one associated with each disk drive, for controlling the transfer of data between the disk drives and the channel buses;

data error correction means, coupled to the common bus, for correcting data errors with respect to specified groups of data; and

array control means coupled to the common bus for selectively configuring the disk drives into logical groups of at least one disk drive each to receive and store related data from the computer, for selectively enabling the data error correction means to be operative with respect to any logical group, for maintaining a plurality of disk drives as spare disk drives for subsequent replacement of a failed disk drive in any logical group, for dividing related data received from the computer into portions for storage in different disk drives of a group specified to store the data and providing the divided data to the common bus for storage in the appropriate disk drives via the channel controllers and disk controllers, and for obtaining previously divided related data from the disk drives and combining it for provision to the computer.

46. A disk drive system as in claim 45 wherein the error correction means includes first means for implementing a first error correction function in which first parity data is calculated with respect to data from the computer to be stored in a specified group of disk drives, wherein the calculated parity data is stored in the group along with the data from the computer.

47. A disk drive system as in claim 46 wherein for any group of disk drives for which the first means of the error correction means is enabled, space equal to the storage capacity of one disk drive is allocated for storage of first parity data.

48. A disk drive system as in claim 46 wherein the error correction means includes second means for implementing a second error correction function in which second parity data is calculated with respect to data from the computer to be stored in a specified group of disk drives, wherein the calculated second parity data is stored in the group along with the data from the computer, wherein the array control means can selectively enable either or both of the first and second means.

49. A disk drive system as in claim 48 wherein for any group of disk drives for which the first means or second means of the error correction means is enabled, space equal to the storage capacity of one disk drive is allocated for storage of first or second parity data generated by the first or second means, respectively.

56. A configurable arrayed storage device system for providing memory to a host computer, comprising:

a plurality of storage devices; and

array control means for selectively defining any combination of one or more logical groups of storage devices in which each group includes at least one storage device and in which the combination employs up to the plurality of storage devices, and for selectively assigning storage devices from among the plurality to form the logical groups, the array control means including (a) storage device control processing means coupled to the storage devices to control read/write operations of each storage device, and (b) system control processing means, coupled to the storage device control processing means, for receiving read/write requests for any logical group from the host computer and controlling the storage device control processing means to cause appropriate read/write operations to occur with respect to each storage device in the logical group for which the request was received, wherein each logical group is accessed by the host computer as if it were a separate single storage device.

57. A configurable arrayed storage device system for providing memory to a host computer, comprising:

a plurality of storage devices;

a common bus for transmitting data to and from each of the storage devices;

array control means for selectively configuring at least some of the storage devices into one or more logical groups of at least one storage device each, for dividing data received from the host computer to be stored in any particular group into designated portions and for providing the designated portions to the common data bus; and

controller means coupled between the common data bus and the storage devices, for recognizing and transmitting each designated portion of data to a particular storage device for storage.