Storage unit replacement using point-in-time snap copy

Patent metadata

Field	Value
Publication number	US-9619331-B2
Application number	US-201414158779-A
Country	US
Kind code	B2
Filing date	Jan 18, 2014
Priority date	Jan 18, 2014
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

In one embodiment, I/O operations may be swapped from an original storage unit to a replacement storage unit in a manner which can reduce or eliminate delays caused by copying of data from the original storage unit to the replacement storage unit. A point-in-time snap copy relationship between the original storage unit and the replacement storage unit of storage locations is established and I/O operations are swapped from the original storage unit to the replacement storage unit. The I/O operations are resumed, accessing the replacement storage unit instead of the original storage unit in the input/output operations issued by the at least one host. Other aspects are described.

First claim

What is claimed is:

1. A method, comprising:
accessing storage locations of an original storage unit in response to received input/output operations, wherein the accessing includes at least one of writing updates to and reading data from the storage location being accessed;
quiescing input/output operations to the original source storage unit;
after quiescing input/output operations to the original source storage unit, creating a point-in-time snap copy of the original storage unit as a replacement storage unit of storage locations and swapping the replacement storage unit for the original source storage unit; and
initiating accessing storage locations of the replacement storage unit instead of storage locations of the original storage unit, in response to received input/output operations, wherein the accessing includes unquiescing input/output operations and at least one of writing updates to and reading data from the storage location of the replacement storage unit being accessed.

2. The method of claim 1 , further comprising background copying data from storage locations of the original storage unit to storage locations of the replacement storage unit after initiation of the accessing of storage locations of the replacement storage units instead of storage locations of the original source storage units.

3. The method of claim 1 wherein the swapping includes a swap manager maintaining a data structure identifying a storage unit to be accessed by the input/output operations issued by at least one host to access storage locations of the identified storage unit, and wherein the accessing of storage locations of the original source storage unit in response to received input/output operations includes at least one of writing updates to and reading data from storage locations of the original source storage unit identified by the data structure maintained by the swap manager.

4. The method of claim 3 wherein the swapping includes the swap manager modifying a data structure to identify the replacement storage unit instead of the original storage unit to be accessed by the input/output operations issued by the at least one host so that storage locations of the replacement storage unit are accessed instead of storage locations of the original source storage unit, in response to received input/output operations.

5. The method of claim 2 wherein the creating a point-in-time snap copy of the original storage unit as a replacement storage unit of storage locations includes creating a point-in-time snap copy relationship between the storage locations of the original storage unit and the storage locations of the replacement storage unit.

6. The method of claim 5 further comprising determining when the background copying of data from storage locations of the original storage unit to storage locations of the replacement storage unit is completed and terminating the point-in-time snap copy relationship between the storage locations of the original storage unit and the storage locations of the replacement storage unit upon completion of the background copying of data from storage locations of the original storage unit to storage locations of the replacement storage unit.

7. The method of claim 1 wherein the quiescing includes queuing input/output operations in a queue and wherein the initiating of accessing of storage locations of the replacement storage unit instead of storage locations of the original source storage unit, in response to received input/output operations includes performing the input/output operations queued in the queue wherein the replacement storage unit is accessed instead of the original storage unit in the queued input/output operations and at least one of updates are written to and data read from storage locations of the replacement storage unit.

8. A system, comprising:
at least one storage subsystem including a plurality of original source storage units, a plurality of original target storage units, a plurality of replacement source storage units and at least one storage controller adapted to access and control storage units of the at least one storage subsystem; and
at least one computer readable storage medium having computer readable program code embodied therein that is enabled to cause operations to be performed, the operations comprising:
accessing storage locations of an original storage unit in response to received input/output operations, wherein the accessing includes at least one of writing updates to and reading data from the storage location being accessed;
quiescing input/output operations to the original source storage unit;
after quiescing input/output operations to the original source storage unit, creating a point-in-time snap copy of the original storage unit as a replacement storage unit of storage locations and swapping the replacement storage unit for the original source storage unit; and
initiating accessing storage locations of the replacement storage unit instead of storage locations of the original storage unit, in response to received input/output operations, wherein the accessing includes unquiescing input/output operations and at least one of writing updates to and reading data from the storage location of the replacement storage unit being accessed.

9. The system of claim 8 , wherein the operations further comprise background copying data from storage locations of the original storage unit to storage locations of the replacement storage unit after initiation of the accessing of storage locations of the replacement storage units instead of storage locations of the original source storage units.

10. The system of claim 8 wherein the swapping includes a swap manager maintaining a data structure identifying a storage unit to be accessed by the input/output operations issued by at least one host to access storage locations of the identified storage unit, and wherein the accessing of storage locations of the original source storage unit in response to received input/output operations includes at least one of writing updates to and reading data from storage locations of the original source storage unit identified by the data structure maintained by the swap manager.

11. The system of claim 10 wherein the swapping includes the swap manager modifying a data structure to identify the replacement storage unit instead of the original storage unit to be accessed by the input/output operations issued by the at least one host so that storage locations of the replacement storage unit are accessed instead of storage locations of the original source storage unit, in response to received input/output operations.

12. The system of claim 9 wherein the creating a point-in-time snap copy of the original storage unit as a replacement storage unit of storage locations includes creating a point-in-time snap copy relationship between the storage locations of the original storage unit and the storage locations of the replacement storage unit.

13. The system of claim 12 wherein the operations further comprise determining when the background copying of data from storage locations of the original storage unit to storage locations of the replacement storage unit is completed and terminating the point-in-time snap copy relationship between the storage locations of the original storage unit and the storage locations of the replacement storage unit upon completion of the background copying of data from storage locations of the original storage unit to storage locations of the replacement storage unit.

14. The system of claim 8 wherein the quiescing includes queuing input/output operations in a queue and wherein the initiating of acce

Assignees

• IBM

Inventors

• Blea Amy N
• Blea David Randall
• Mcbride Gregory E
• Rooney William J
• Wolfgang John Jay

Classifications

• G06F11/1662

  the resynchronized component or unit being a persistent storage device (re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008) · CPC title

• G06F2201/84

  Using snapshots, i.e. a logical point-in-time copy of the data · CPC title

• G06F3/0611

  in relation to response time · CPC title

• G06F11/1451

  by selection of backup contents · CPC title

• G06F11/2069 Primary

  Management of state, configuration or failover · CPC title