Methods and apparatuses for providing copies of stored data for disaster recovery and other uses

• US 7,441,052 B2
• Filed: 09/29/2003
• Issued: 10/21/2008
• Est. Priority Date: 09/29/2003
• Status: Expired due to Fees

• Current Assignee: Hitachi Data Systems Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi Data Systems Corporation (Hitachi, Ltd.)
• Inventors: Demaray, Milton W., Attanese, Thomas A.
• Primary Examiner(s): Hafiz; Tariq R.
• Assistant Examiner(s): SUN, SCOTT C
• Application Number:
  US10/674,805
• Publication Number:
  US 20050081098A1
• Time in Patent Office: 1,849 Days
• Field of Search: 710/9, 710/16, 711/221, 707/204
• US Class Current: 710/9
• CPC Class Codes: G06F 11/006 Identification G06F11/2289 takes precedence
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover
• CPC Class Codes: G06F 11/2082 Data synchronisation

Abstract

A disaster recovery technique for computer systems obtains backup copies of data by arranging recording devices like direct-access disk devices into copy pairs of primary and secondary devices. Management of the device copy pairs within a single system and across multiple systems is facilitated by constructing maps of device information that provide a cross-reference between I/O subsystem device numbers and hardware addresses. Information structures are constructed from the maps and used to facilitate defining and managing groups of device copy pairs.

Claims

1. In a system comprising a first computer coupled to first and second storage devices, a method for providing copies of data, the method comprising:

cross-referencing (a) a hardware address identifying the first storage device and (b) a first device identifier for representing the first storage device to a program in the first computer;

cross-referencing (a) a hardware address identifying the second storage device and (b) a first device identifier for representing the second storage device to a program in the first computer;

pairing the first and second storage devices;

adding the pair, by information other than first device identifiers, to a copy group already containing another storage-device pair;

identifying the copy group;

cross-referencing the copy-group identifier and the first device identifiers of the pair; and

preparing to copy data, using the cross-reference.

2. The method according to claim 1 that comprises:

receiving a first input specifying one or more first device identifiers;

obtaining one or more hardware addresses in response to the first input; and

establishing the first map by associating the one or more hardware addresses with one or more first device identifiers.

3. The method according to claim 2, wherein:

the first computer receives the first input and, in response, sends one or more commands to a respective controller;

the respective controller obtains at least some of the one or more hardware addresses in response to the one or more commands by interrogating either or both of control information in the respective controller and recording devices coupled to the respective controller, and sends the obtained hardware addresses to the first computer; and

the first computer establishes the first map.

4. The method according to claim 3, wherein:

the first computer comprises a channel subsystem that controls transfers of data between the first computer and one or more recording devices coupled to the respective controller;

the first computer is coupled to the respective controller by a first data communication path that is a channel path coupled to the channel subsystem;

the one or more commands are conveyed to the respective controller by a channel program comprising one or more channel command words generated by the channel subsystem; and

hardware addresses obtained by the respective controller are conveyed to the first computer through the first data communication path as one or more responses to the channel program.

5. The method according to claim 3, wherein the respective controller determines whether a respective recording device is capable of responding to a query command and returns the hardware address of the respective recording device only if the respective recording device is capable of responding to the query command.

6. The method according to claim 1, wherein

each of the plurality of recording devices has a recording medium with a medium identifier that identities the recording medium, and

the first map also provides a cross-reference between medium identifiers and either or both of hardware addresses and first device identifiers for respective recording devices, and

wherein the method comprises:

establishing the copy-group map also to provide a cross-reference between the copy-group identifier and the medium identifiers for the one or more pairs of recording devices assigned to the copy group.

7. The method according to claim 1, wherein the system comprises

a second computer coupled to one or more controllers of which at least one of the controllers is coupled to one or more recording devices that are in the one or more pairs of recording devices assigned to the copy group,

the method comprising:

obtaining a second map that provides a cross-referencc between the hardware address of the respective recording device and a second device identifier that is associated with the respective recording device, wherein the second device identifier represents the respective recording device to programs executing in the second computer; and

establishing the copy-group map also to provide a cross-reference between the copy-group identifier and the second device identifiers of the one or more recording devices that are in the one or more pairs of recording devices assigned to the copy group.

8. The method according to claim 7 that comprises:

receiving a second input specifying one or more second device identifiers;

obtaining one or more hardware addresses in response to the second input; and

establishing the second map by associating the one or more hardware addresses with the one or more second device identifiers.

9. The method according to claim 8, wherein:

the second computer receives the second input and, in response, sends one or more commands to a respective controller;

the respective controller obtains at least some of the one or more hardware addresses in response to the one or more commands by interrogating either or both of control information in the respective controller and recording devices coupled to the respective controller, and sends these obtained hardware addresses to the second computer; and

the second computer establishes the second map.

10. The method according to claim 9, wherein:

the second computer comprises a channel subsystem that controls transfers of data between the second computer and one or more recording devices coupled to the respective controller;

the second computer is coupled to the respective controller by a second data communication path that is a channel path coupled to the channel subsystem;

the one or more commands are conveyed to the respective controller by a channel program comprising one or more channel command words generated by the channel subsystem; and

hardware addresses obtained by the respective controller are conveyed to the second computer through the second data communication path as one or more responses to the channel program.

11. A storage medium wherein is located a computer program for executing the method of claim 1.

12. A storage medium wherein is located a computer program for executing the method of claim 2.

13. A storage medium wherein is located a computer program for executing the method of claim 3.

14. A storage medium wherein is located a computer program for executing the method of claim 4.

15. A storage medium wherein is located a computer program for executing the method of claim 5.

16. A storage medium wherein is located a computer program for executing the method of claim 6.

17. A storage medium wherein is located a computer program for executing the method of claim 7.

18. A storage medium wherein is located a computer program for executing the method of claim 8.

19. A storage medium wherein is located a computer program for executing the method of claim 9.

20. A storage medium wherein is located a computer program for executing the method of claim 10.

21. A computer system comprising

a CPU;

the storage medium of claim 11; and

a bus coupling the CPU and the storage medium.

22. A computer system comprising:

a CPU;

the storage medium of claim 12; and

a bus coupling the CPU and the storage medium.

23. A computer system comprising:

a CPU;

to the storage medium of claim 13; and

a bus coupling the CPU and the storage medium.

24. A computer system comprising:

a CPU;

the storage medium of claim 14; and

a bus coupling the CPU and the storage medium.

25. A computer system comprising:

a CPU;

the storage medium of claim 15; and

a bus coupling the CPU and the storage medium.

26. A computer system comprising:

a CPU;

the storage medium of claim 16; and

a bus coupling the CPU and the storage medium.

27. A computer system comprising:

a CPU;

the storage medium of claim 17; and

a bus coupling the CPU and the storage medium.

28. A computer system comprising:

a CPU;

the storage medium of claim 18; and

a bus coupling the CPU and the storage medium.

29. A computer system comprising:

a CPU;

the storage medium of claim 19; and

a bus coupling the CPU and the storage medium.

30. A computer system comprising:

a CPU;

the storage medium of claim 20; and

a bus coupling the CPU and the storage medium.

31. The method of claim 1 wherein the preparing to copy data comprises

preparing to recover data.

32. The method of claim 1 further comprising:

recovering data, using the cross-reference.