I/O response times in data replication environments

Patent metadata

Field	Value
Publication number	US-10838625-B2
Application number	US-201816153727-A
Country	US
Kind code	B2
Filing date	Oct 6, 2018
Priority date	Oct 6, 2018
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

A method for improving I/O response times in a data replication environment is disclosed. In one embodiment, such a method includes receiving, at a primary storage system, a request to read data on the primary storage system. The method starts a timer upon receiving the request. In the event the data cannot be retrieved from the primary storage system by the time the timer expires, the method requests the data from a secondary storage system. In the event the primary storage system returns the data before the secondary storage system, the method returns data retrieved from the primary storage system to a host system. In the event the secondary storage system returns the data before the primary storage system, the method returns the data retrieved from the secondary storage system to the host system. A corresponding system and computer program product are also disclosed.

First claim

The invention claimed is:

1. A method for improving I/O response times in a data replication environment, the method comprising:
receiving, at a primary storage system from a host system, a request to read data on the primary storage system;
upon receiving the request, starting a timer configured to expire after a designated time period has elapsed;
in the event the data cannot be retrieved from the primary storage system by the time the timer expires, requesting, by the primary storage system, the data from a secondary storage system;
in the event the primary storage system returns the data before the secondary storage system, returning the data retrieved from the primary storage system to the host system;
in the event the secondary storage system returns the data before the primary storage system, returning the data retrieved from the secondary storage system to the host system; and
modifying the designated time period for future requests to read data on the primary storage system based on which of the primary storage system and the secondary storage system is first to return the data.

2. The method of claim 1 , further comprising, in the event the primary storage system returns the data before the secondary storage system, increasing the designated time period for future requests to read data on the primary storage system.

3. The method of claim 2 , wherein increasing the designated time period comprises increasing the designated time period until a maximum value is reached.

4. The method of claim 1 , further comprising, in the event the secondary storage system returns the data before the primary storage system, decreasing the designated time period for future requests to read data on the primary storage system.

5. The method of claim 4 , wherein decreasing the designated time period comprises decreasing the designated time period until a minimum value is reached.

6. The method of claim 1 , further comprising, in the event the primary storage system returns the data before the secondary storage system, discarding the data received from the secondary storage system.

7. The method of claim 1 , further comprising, in the event the secondary storage system returns the data before the primary storage system, discarding the data received from the primary storage system.

8. A computer program product for improving I/O response times in a data replication environment, the computer program product comprising a computer-readable storage medium having computer-usable program code embodied therein, the computer-usable program code configured to perform the following when executed by at least one processor:
receive, at a primary storage system from a host system, a request to read data on the primary storage system;
upon receiving the request, start a timer configured to expire after a designated time period has elapsed;
in the event the data cannot be retrieved from the primary storage system by the time the timer expires, request, by the primary storage system, the data from a secondary storage system;
in the event the primary storage system returns the data before the secondary storage system, return the data retrieved from the primary storage system to the host system;
in the event the secondary storage system returns the data before the primary storage system, return the data retrieved from the secondary storage system to the host system; and
modify the designated time period for future requests to read data on the primary storage system based on which of the primary storage system and the secondary storage system is first to return the data.

9. The computer program product of claim 8 , wherein the computer-usable program code is further configured to, in the event the primary storage system returns the data before the secondary storage system, increase the designated time period for future requests to read data on the primary storage system.

10. The computer program product of claim 9 , wherein increasing the designated time period comprises increasing the designated time period until a maximum value is reached.

11. The computer program product of claim 8 , wherein the computer-usable program code is further configured to, in the event the secondary storage system returns the data before the primary storage system, decrease the designated time period for future requests to read data on the primary storage system.

12. The computer program product of claim 11 , wherein decreasing the designated time period comprises decreasing the designated time period until a minimum value is reached.

13. The computer program product of claim 8 , wherein the computer-usable program code is further configured to, in the event the primary storage system returns the data before the secondary storage system, discard the data received from the secondary storage system.

14. The computer program product of claim 8 , wherein the computer-usable program code is further configured to, in the event the secondary storage system returns the data before the primary storage system, discard the data received from the primary storage system.

15. A system for improving I/O response times in a data replication environment, the system comprising:
at least one processor;
at least one memory device operably coupled to the at least one processor and storing instructions for execution on the at least one processor, the instructions causing the at least one processor to:
receive, at a primary storage system from a host system, a request to read data on the primary storage system;
upon receiving the request, start a timer configured to expire after a designated time period has elapsed;

in the event the data cannot be retrieved from the primary storage system by the time the timer expires, request, by the primary storage system, the data from a secondary storage system;
in the event the primary storage system returns the data before the secondary storage system, return the data retrieved from the primary storage system to the host system;
in the event the secondary storage system returns the data before the primary storage system, return the data retrieved from the secondary storage system to the host system; and
modify the designated time period for future requests to read data on the primary storage system based on which of the primary storage system and the secondary storage system is first to return the data.

16. The system of claim 15 , wherein the instructions further cause the at least one processor to, in the event the primary storage system returns the data before the secondary storage system, increase the designated time period for future requests to read data on the primary storage system.

17. The system of claim 16 , wherein increasing the designated time period comprises increasing the designated time period until a maximum value is reached.

18. The system of claim 15 , wherein the instructions further cause the at least one processor to, in the event the secondary storage system returns the data before the primary storage system, decrease the designated time period for future requests to read data on the primary storage system.

19. The system of claim 18 , wherein decreasing the designated time period comprises decreasing the designated time period until a minimum value is reached.

20. The system of claim 15 , wherein the instructions further cause the at least one processor to:
in the event the primary storage system returns the data before the secondary storage system, discard the data received from the secondary storage system; an

Assignees

• IBM

Inventors

• Sorenson Todd C
• Nielsen Karl A
• Sheppard Jacob L
• Riley Sean P
• Juarez Larry

Classifications

• G06F13/20 Primary

  for access to input/output bus · CPC title

• G06F3/065

  Replication mechanisms · CPC title

• G06F3/0673

  Single storage device · CPC title

• G06F2212/1024

  Latency reduction · CPC title

• G06F3/0635

  by changing the path, e.g. traffic rerouting, path reconfiguration · CPC title