Data storage controller providing multiple hosts with access to multiple storage subsystems

• US 6,073,209 A
• Filed: 03/31/1997
• Issued: 06/06/2000
• Est. Priority Date: 03/31/1997
• Status: Expired due to Term

• Current Assignee: NetApp, Inc.
• Original Assignee: Ark Research Corp (Broadcom, Inc.)
• Inventors: Bergsten, James R.
• Primary Examiner(s): Nguyen, Hiep T.
• Application Number:
  US08/828,888
• Time in Patent Office: 1,163 Days
• Field of Search: 707/204, 711/162, 711/148, 711/114, 711/153, 714/6
• US Class Current: 711/114
• CPC Class Codes: G06F 11/201 between storage system components
• CPC Class Codes: G06F 11/2058 using more than 2 mirrored copies
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• 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
• CPC Class Codes: G06F 13/1657 Access to multiple memories
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99954 Version management
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A computer network comprises a number of storage controllers, each coupled to one of a plurality of storage arrays, each storage array including at least one mass storage device. Each storage controller may be coupled to at least one host processing system and to at least one other storage controller to control access of the host processing systems to the mass storage devices. Multiple copies of data are maintained in storage arrays that are geographically remote to each other, such that any copy can be accessed by any host. Each storage controllers includes an interface with a host that emulates a mass storage device and an interface with a local storage array that emulates a host. The interfaces to the host and local storage arrays are independent of the type of host or devices in the local storage array. Two or more hosts may be dissimilar to each other, and two or more storage arrays may include dissimilar mass storage devices. Hosts access stored data using virtual addressing. During a data access, the storage controller connected to the accessing host maps a virtual address provided by the host to a real physical location in any of the storage arrays, such that the actual location of the data is transparent to the host. The storage controllers provide automatic back-up and error correction as well as write protection of back-up copies.

Claims

1. A storage controller, comprising:

a host interface providing a data interface with at least one host processing system independent of a device type of each said at least one host processing system, the storage controller physically separate from each said at least one host processing system;

a storage interface providing a data interface with at least one storage array, the storage controller physically separate from each said at least one storage array, each said at least one storage array including at least one mass storage device, the storage interface further providing the data interface with said at least one storage array independent of the device type(s) of the mass storage devices in each said array; and

control circuitry coupled to the host interface and the data interface, the control circuitry configured to enable said at least one host processing system to access each said at least one storage array, such that the presence of the storage controller is transparent to each said at least one host processing system and each said at least one storage array.

2. A storage controller according to claim 1, wherein each said at least one host processing system has a hardware configuration and a software configuration, wherein the storage controller is configured to enable said at least one host processing system to access said at least one storage array regardless of the hardware configuration or the software configuration(s) of said at least one host processing system.

3. A storage controller according to claim 1, wherein the storage controller is configured to enable said at least one host processing system to access a mass storage device having any of a plurality of different device types.

4. A storage controller according to claim 1, wherein the storage controller is configured to:

receive from one of said at least one host processing system a request specifying a virtual storage location of data; and

determine a physical storage location of the data based on the request.

5. A storage controller according to claim 4, wherein the virtual storage location corresponds to a plurality of physical storage locations distributed among a plurality of mass storage devices.

6. A storage controller according to claim 1, wherein:

the storage controller is coupled to a local storage array;

the storage controller is further coupled to a remote storage controller;

the remote storage controller is coupled to a remote host processing system; and

the storage controller is further configured to provide the remote host processing system with access to the local storage array.

7. A storage controller according to claim 6, wherein the remote storage controller is coupled to a remote storage array, wherein the storage controller is further configured to provide the local host processing system with access to data stored in the remote storage array.

8. A storage controller according to claim 1, wherein each of a plurality of copies of a set of data is stored on a different one of the mass storage devices, each copy of the set of data having a plurality of subsets, and wherein the storage controller is configured to access a different subset of the set of data in each of the plurality of copies to access the complete set of data.

9. A storage controller according to claim 1, wherein a first one of the storage arrays may comprise mass storage devices having a different storage medium than a second one of the storage arrays.

10. A storage controller according to claim 1, wherein:

said at least one host processing systems comprises at least three host processing systems; and

said at least one storage array comprises at least three storage arrays.

11. A storage controller according to claim 1, wherein the control circuitry is configured to communicate with a plurality of other storage controllers.

12. A data storage controller for providing a plurality of host processing systems with access to a plurality of storage arrays, each of the storage arrays including a plurality of mass storage devices, the data storage controller comprising:

a processor; and

a memory coupled to the processor, the memory having instructions stored therein which, when executed by the processor, cause the data storage controller to;

provide a data interface with a local host processing system independent of a device type of the local host processing system, the storage controller physically separate from the local host processing system;

emulate a local storage array to the local host processing system, such that the presence of the storage controller is functionally transparent to the local host processing system;

provide a data interface with the local storage array independent of the type of mass storage devices in the local storage array, the storage controller physically separate from the local storage array;

emulate the host processing system to the mass storage devices of the local storage array, such that the presence of the storage controller is transparent to the local storage array;

provide an interface to a remote data storage controller, the remote data storage controller for coupling to a remote storage array; and

control communication of data such that any of the plurality of host processing systems can access data in any of the plurality of storage arrays.

13. A data storage controller according to claim 12, wherein the instructions further comprise instructions which, when executed by the processor, cause the data storage controller to receive from one of the host processing systems a request specifying a virtual storage location of a data block and to determine a real storage location of the data block based on the virtual storage location.

14. A data storage controller according to claim 12, wherein the instructions further comprise instructions which, when executed by the processor, allow the data storage controller to provide any of the host processing systems with access to any of the storage arrays using virtual addresses, such that actual locations of stored data in the storage arrays are transparent to the host processing systems.

15. A data storage controller according to claim 14, wherein one of the virtual addresses may be mapped to a plurality of real storage locations distributed among a plurality of the mass storage devices.

16. A data storage controller according to claim 12, wherein the instructions further comprise instructions which, when executed by the processor, cause the data storage controller to provide a remote host processing system of the plurality of host processing systems with access to the local storage array, the remote host processing system coupled to the remote data storage controller.

17. A data storage controller according to claim 16, wherein the remote storage controller is coupled to a remote storage array, and wherein the instructions further comprise instructions which, when executed by the processor, cause the data storage controller to provide the local host processing system with access to data stored in the remote storage array.

18. A data storage controller according to claim 12, wherein the data storage controller is coupled to the host processing system via a SCSI interface.

19. A data storage controller according to claim 18, wherein the data storage controller is coupled to the local storage array via a SCSI interface.

20. A data storage controller according to claim 12, further comprising means for connecting a mass storage device having any of a plurality of different device types to the host processing system.

21. A data storage controller according to claim 20, wherein a first one of the storage arrays may comprise mass storage devices having a different storage medium than a second one of the storage arrays.

22. A data storage controller according to claim 12, wherein the local host processing system has a hardware configuration and a software configuration, the data storage controller further comprising means for providing the data interface to the host processing system, such that the local host processing system can access the local storage array independent of both the hardware configuration and the software configuration of the local host processing system.

23. A data storage controller according to claim 12, wherein:

the plurality of processing systems includes at least three host processing systems; and

the plurality of storage arrays includes at least three storage arrays.

24. A data storage controller according to claim 12, wherein the instructions which cause the data storage controller to control communication of data comprise instructions which, when executed by the processor, cause the data storage controller to communicate with a plurality of other data storage controllers.

25. In a storage controller coupled to a plurality of host processing systems and a plurality of storage arrays, a method of providing the plurality of host processing systems with access to the plurality of storage arrays, the plurality of host processing systems including a local host processing system, the plurality of storage arrays including a local storage array, each of the storage arrays including a plurality of mass storage devices, the method comprising:

providing a data interface with the local host processing system, the host processing system physically separate from the storage controller;

emulating the local storage array, such that the presence of the storage controller is transparent to the local host processing system;

providing a data interface with the local storage array, the local storage array physically separate from the storage controller, wherein the local storage array may include any of a plurality of different storage mediums;

emulating the local host processing system, such that the presence of the storage controller is transparent to the local storage array;

providing an interface to a remote data storage controller coupled to a remote storage array of the plurality of storage arrays; and

controlling communication of data such that any of the plurality of host processing systems can access data in any of the plurality of storage arrays.

26. A method according to claim 25, wherein the local storage array includes mass storage devices of a first storage medium, and the remote storage array includes mass storage devices of a second storage medium different from the first storage medium.

27. A method according to claim 25, further comprising the step of providing the host processing system with access to the storage arrays using virtual addressing, wherein physical locations of data stored in the storage arrays are transparent to the host processing systems.

28. A method according to claim 25, wherein the plurality of processing systems comprises at least three host processing systems.

29. A method according to claim 28, wherein the plurality of storage arrays comprises at least three storage arrays.

30. A method according to claim 25, wherein the step of controlling communication of data comprises the step of communicating with a plurality of other storage controllers to cause a plurality of copies of a set of data to be stored distributed among the plurality of storage arrays.

31. A system comprising:

a plurality of host processing systems;

a plurality of storage arrays, each of the storage arrays including at least one mass storage device; and

a plurality of storage controllers, each of the storage controllers coupled to one of the host processing systems and physically separate from the host processing systems, each of the storage controllers coupled to one of the storage arrays and physically separate from the storage arrays, each of the storage controllers further coupled to another one of the storage controllers, each of the storage controllers having a first interface with one of the host processing systems, the first interface for emulating a mass storage device such that the presence of the storage controller is transparent to the host processing systems, each of the storage controllers further having a second interface with a local storage array, the second interface for emulating a host processing system such that the presence of the storage controller is transparent to storage arrays, the plurality of storage controllers cooperating to permit any of the host processing systems to access data stored in any of the storage arrays.

32. A system according to claim 31, wherein for each of the storage controllers, the second interface is capable of interfacing with mass storage devices having any of a plurality of different device types.

33. A system according to claim 32, wherein two or more of the storage arrays may use dissimilar storage media.

34. A system according to claim 31, wherein the plurality of processing systems comprises at least three host processing systems.

35. A systems comprising:

a plurality of host processing systems;

a plurality if storage arrays, each of the storage arrays including at least one mass storage device; and

a plurality of storage controllers, each of the storage controllers coupled to one of the host processing systems and physically separate from said one of the host processing systems, coupled to one of the storage arrays and physically separate from said one of the storage arrays, and coupled to another one of the storage controllers, wherein the storage controllers cooperate to permit any of the host processing systems to access data stored in any of the storage arrays, each of the storage controllers including means for supporting any one of a plurality of types of mass storage media in a corresponding one of the storage arrays, wherein the presence of each of the storage controllers is transparent to each of the host processing systems and each of the storage arrays.

36. A system according to claim 35, wherein each of the storage controllers further comprises means for supporting any one of a plurality of configurations of a corresponding host processing system.

37. A system according to claim 36, each of the storage controllers comprising an interface with a host processing system for emulating a mass storage device and an interface with a local storage array for emulating a host processing system.

38. A system according to claim 37, each of the storage devices further comprising translation means for representing the storage arrays as at least one virtual device to the host processing systems.

39. A system according to claim 35, wherein the storage controllers function as peers with respect to each other.

40. A system according to claim 35, wherein the plurality of processing systems comprises at least three host processing systems.