Fast data copy using a data copy track table

• US 20030187887A1
• Filed: 04/01/2002
• Published: 10/02/2003
• Est. Priority Date: 04/01/2002
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Beal, David G.
• Granted Patent: US 7,082,445 B2
• Time in Patent Office: Days
• US Class Current: 707/204
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A data structure, method, and computer system for fast data copy is provided which uses control structures in a data copy track table. The control structures include a physical location pointer, a physical location pointer flag, a forward track pointer and a backward source pointer. These control structures are used in an update-in-place architecture. Requests for source or target data updates do not require additional write cycles.

Claims

1. A computer-useable memory device encoded with a data structure for copying data from a source volume to a target volume, said data structure having entries, said entries comprising:

a physical location pointer;

a physical location pointer reserved flag;

a forward target pointer; and

,

a backward source pointer.

2. A computer implemented method of performing a copy of data from a source volume to a target volume, comprising:

(a) using a data copy track table having a control structure for the source volume and a control structure for the target volume, each of said control structures comprising a physical location pointer, a physical location pointer reserved flag, a forward target pointer, and a backward source pointer;

(b) receiving a request to copy the data from the source volume to the target volume;

(c) updating the physical location pointer for the source volume to indicate the location of the data in the source volume when the physical location pointer reserved flag for the source volume is not set;

(d) setting the physical location pointer reserved flag for the source volume;

(e) updating the forward target pointer of the source volume to the control structure for the target volume;

(f) unsetting the physical location pointer reserved flag of the target volume;

(g) setting the forward track pointer of the target volume to a null value;

(h) setting the backward source pointer of the source volume to a null value; and

,

(i) setting the backward source pointer of the target volume to the data copy track table control structure for the target volume.

3. A method as in claim 2 wherein said data copy track table exists in nonvolatile memory.

4. A method as in claim 2 wherein said method is used in an update-in-place architecture.

5. A method of claim 2, wherein the source and target volumes are virtual volumes created using a data copy track table.

6. A method of claim 2, wherein the source and target volumes are physical volumes.

7. A computer implemented method of performing an update of data in a source volume having a copy chain relationship with a target volume, comprising:

(a) using a data copy track table having an entry for the source volume and entry for the target volume, each of said entries comprising a physical location pointer, a physical location pointer reserved flag, a forward target pointer, and a backward source pointer;

(b) receiving a request to update the data in the source volume;

(c) updating the physical location pointer for the source volume to indicate the location of the allocated tracks in the target volume when the physical location pointer reserved flag for the source volume is set;

(d) setting the physical location pointer reserved flag for the target volume;

(e) the physical location pointer for the target volume is updated to indicate the track location in the source volume;

(f) setting the forward target pointer of the source volume to NULL;

(g) maintaining the forward track pointer of the target volume to NULL;

(h) maintaining the backward space pointer of the source volume to NULL;

(i) setting the backward source pointer of the target volume to a null value; and

,

(j) writing the updated source data to the tracks in the target volume.

8. A method as in claim 7 wherein the data copy track table exists in nonvolatile memory.

9. A method as in claim 7 wherein said method is used in an update-in-place architecture.

10. A method of claim 7, wherein the source and target volumes are virtual volumes created using a data copy track table.

11. A method of claim 7, wherein the source and target volumes are physical volumes.

12. A system for performing a copy of data, comprising:

(a) a computer having a data storage device connected thereto; and

(b) one or more computer programs, executed by the computer, for;

(i) using a data copy track table having an entry for the source volume and entry for the target volume, each of said entries comprising a physical location pointer, a physical location pointer reserved flag, a forward target pointer, and a backward source pointer;

(ii) receiving a request to copy the data from the source volume to the target volume;

(iii) updating the physical location pointer for the source volume to indicate the location of the source volume;

(iv) setting the physical location pointer reserved flag for the source volume;

(v) setting the forward target pointer of the source volume to the location in the target volume;

(vi) unsetting the physical location pointer reserved flag of the target volume;

(vii) setting the forward track pointer of the target volume to a null value;

(viii) setting the backward source pointer of the source volume to a null value;

(ix) setting the backward source pointer of the target volume to the data copy track table entry for the target volume.

13. A system as in claim 12 wherein the data copy track table exists in nonvolatile memory.

14. A system as in claim 12 wherein said system is used in an update-in-place architecture.

15. A system of claim 12, wherein the source and target volumes are virtual volumes created using a data copy track table.

16. A system of claim 12, wherein the source and target volumes are physical volumes.

17. An computer-useable medium whose contents cause a processor to perform a backup of source data, comprising:

(a) using a data copy track table having a control structure for the source volume and a control structure for the target volume, each of said control structures comprising a physical location pointer, a physical location pointer reserved flag, a forward target pointer, and a backward source pointer;

(b) receiving a request to copy the data from the source volume to the target volume;

(c) updating the physical location pointer for the source volume to indicate the location of the data in the source volume when the physical location pointer reserved flag for the source volume is not set;

(d) setting the physical location pointer reserved flag for the source volume;

(e) updating the forward target pointer of the source volume to the control structure for the target volume;

(f) unsetting the physical location pointer reserved flag of the target volume;

(g) setting the forward track pointer of the target volume to a null value;

(h) setting the backward source pointer of the source volume to a null value; and

,

(i) setting the backward source pointer of the target volume to the data copy track table control structure for the target volume.

18. A computer-useable medium as in claim 17 wherein the data copy track table exists in nonvolatile memory.

19. A computer-useable medium as in claim 17 wherein said computer-readable medium is used in an update-in-place architecture.

20. A computer-useable medium of claim 17, wherein the source and target volumes are virtual volumes created using a data copy track table.

21. A computer-useable medium of claim 17, wherein the source and target volumes are physical volumes.