Read ahead caching of data from cloud storage and method thereof

• US 9,319,265 B2
• Filed: 02/22/2013
• Issued: 04/19/2016
• Est. Priority Date: 02/22/2013
• Status: Active Grant

• Current Assignee: Hitachi Vantara, LLC (Hitachi, Ltd.)
• Original Assignee: Hitachi Data Systems Engineering Uk Limited (Hitachi, Ltd.)
• Inventors: Bloomstein, Jason R., Meadows, Joseph, Bort-Shatsky, Inna
• Primary Examiner(s): Bragdon, Reginald
• Assistant Examiner(s): Wang, Edward
• Application Number:
  US13/774,800
• Publication Number:
  US 20140244937A1
• Time in Patent Office: 1,152 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1748 De-duplication implemented within the file system, e.g. based on file segments de-duplication techniques in storage systems for the management of data blocks G06F3/0641
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching

Abstract

A high tier storage area stores a stub file and a lower tier cloud storage area stores the file corresponding to the stub file. When a client apparatus requests segments of the file from the high tier storage area, reference is made to the stub file to determine a predicted non-sequential pattern of requests to the segments by the client apparatus. The high tier storage area follows the predicted non-sequential pattern of requests to retrieve the segments of the file from the cloud prior to the client apparatus actually requesting the segments. As such, the file may be efficiently provided to the client apparatus while also efficiently storing the file on the lower tier cloud storage area.

Claims

1. A computer system connected over a network to a cloud service, the computer system comprising:

a storage area connected to another computer, and having a file system which includes a stub file representing a file stored with the cloud service; and

a cache and a processor connected to the storage area,

wherein the file is a logical sequence of plural data segments,

wherein an initial request for a first data segment of the file from the another computer to the storage area causes the processor to refer to the stub file, issue a first request to the cloud service for the first data segment of the file stored with the cloud service, and store the first data segment of the file in the cache,

wherein, based on the initial request to the file, the processor issues a second request to the cloud service for a last data segment of the file stored with the cloud service, and stores the last data segment of the file in the cache, and,

wherein, after the second request for the last data segment, the processor issues one or more additional requests to the cloud service for non-sequential intermediate data segments from among an intermediate logical sequence of the data segments of the file stored with the cloud service based on a type of the file, and stores the non-sequential intermediate data segments in the cache,

wherein the non-sequential intermediate data segments are non-sequential within the intermediate logical sequence which includes the data segments of the file other than the first data segment and the last data segment of the file, and

wherein the one or more additional requests to the cloud service are independent of any additional requests from the another computer after the initial request.

2. The computer system of claim 1, wherein any additional requests, after the initial request, for non-sequential data segments of the file from the another computer to the storage area, causes the processor to refer to the cache, and read the non-sequential data segments from the cache corresponding to the additional requests from the another computer.

3. The computer system of claim 1, wherein the one or more additional requests are issued from the processor after the last data segment of the file is stored in the cache.

4. The computer system of claim 1, wherein the non-sequential intermediate data segments are interleaved data segments.

5. The computer system of claim 1, wherein the non-sequential intermediate data segments are 64 k segments.

6. The computer system of claim 1, wherein the stub file includes metadata indicating the type of the file stored with the cloud service.

7. The computer system of claim 1, wherein the file system is CIFS.

8. The computer system of claim 1, wherein the first, second and additional requests to the cloud service are HTTPS requests.

9. The computer system of claim 1, wherein the another computer reads the first, last and non-sequential intermediate data segments from the cache.

10. The computer system of claim 1, wherein the non-sequential intermediate data segments are removed on a FIFO basis from the cache.

11. The computer system of claim 1, wherein the non-sequential intermediate data segments are removed on a least recently accessed basis from the cache.

12. A method of retrieving a file, the method comprising:

storing a file with a cloud service and maintaining a stub file representing the file on a file system of a storage area connected over a network with the cloud service, where the file is a logical sequence of plural data segments;

receiving at the storage area an initial request for a first data segment of the file from another computer connected to the storage area;

referring to the stub file;

issuing a first request from the storage area to the cloud service for the first data segment of the file stored with the cloud service;

storing the first data segment of the file in a cache accessible to the storage area;

issuing, based on the initial request, a second request from the storage area to the cloud service for a last data segment of the file stored with the cloud service;

storing the last data segment of the file in the cache;

issuing, based on a type of the file, one or more additional requests from the storage area to the cloud service for non-sequential intermediate data segments from among an intermediate logical sequence of the data segments of the file stored with the cloud service based on a type of the file; and

storing the non-sequential intermediate data segments in the cache,

wherein the non-sequential intermediate data segments are non-sequential within the intermediate logical sequence which includes the data segments of the file other than the first data segment and the last data segment of the file, and

wherein the one or more additional requests to the cloud service are independent of any additional requests from the another computer after the initial request.

13. The method of claim 12, further comprising:

receiving, at the storage area and after the initial request, the additional requests from the another computer for the non-sequential data segments of the file; and

reading the non-sequential data segments from the cache corresponding to the additional requests from the another computer.

14. The method of claim 12, wherein the one or more additional requests are issued from the storage area after the last data segment of the file is stored in the cache.

15. The method of claim 12, wherein the non-sequential intermediate data segments are interleaved data segments.

16. The method of claim 12, wherein the non-sequential intermediate data segments are 64 k segments.

17. The method of claim 12, wherein the stub file includes metadata indicating the type of the file stored with the cloud service.

18. The method of claim 12, wherein the file system is CIFS.

19. The method of claim 12, wherein the first, second and additional requests to the cloud service are HTTPS requests.

20. The method of claim 12, wherein the another computer reads the first, last and non-sequential intermediate data segments from the cache.

21. The method of claim 12, further comprising:

removing the non-sequential intermediate data segments on a FIFO basis from the cache.

22. The method of claim 12, further comprising:

removing the non-sequential intermediate data segments on a least recently accessed basis from the cache.