Log-structured block system and method

• US 20020103983A1
• Filed: 01/29/2002
• Published: 08/01/2002
• Est. Priority Date: 01/29/2001
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Aune, Dave, Rege, Satish L.
• Granted Patent: US 6,895,468 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/2069 Management of state, configuration or failover

Abstract

A log-structured block system is provided in which writing log-structured data is done. Subsequently data mirroring is done. In addition, a data storage system for implementing the log-structured block system is provided.

Claims

1. A data mirroring method, comprising steps of:

creating a log in memory;

writing one or more logs to a disc drive, the disc drive formatted in such a way as to provide a specific area for writing logs; and

creating a mirror of data based on information stored in the area for writing logs.

2. The method of claim 1 wherein creating a mirror comprises reading the logs from the log area of the disc drive and writing the logs to a specific disc mirror area of a disc array.

3. The method of claim 1 wherein creating a mirror further comprises parsing each log to decide where data stored in the log is to be written on the disc array.

4. The method of claim 1 wherein creating a log in memory comprises creating a header containing a write request and metadata.

5. The method of claim 4 wherein the metadata contains a pointer to the next write request.

6. The method of claim 1 wherein creating a log in memory consists of creating a sequence of logs in memory.

7. The method of claim 6 wherein writing one or more logs to a disc drive comprises writing a sequence of logs to the disc drive.

8. A data storage system, comprising:

(a) at least one first disc drive;

(b) at least one second disc drive; and

(c) a controller, operatively coupled to the at least one first disc drive and the at least one second disc drive, to perform a method of mirroring data, wherein the method of mirroring data comprises

creating a log in memory;

writing one or more logs to the at least one second disc drive, the at least one second disc drive formatted in such a way as to provide a specific area for writing logs; and

creating a mirror of data based on information stored in the area for writing logs.

9. The data storage system of claim 8 wherein the controller further comprises reading the logs from the log area of the at least one second disc drive and writing the logs to a specific area designated for mirroring a specific one of the at least one disc drive.

10. The data storage system of claim 8 wherein creating a log in memory comprises creating a header containing metadata.

11. The data storage system of claim 8 wherein the metadata contains a pointer to the next write request.

12. The data storage system of claim 8 wherein creating a log in memory consists of creating a sequence of logs in memory.

13. The data storage system of claim 8 wherein writing one or more logs to a disc drive comprises writing a sequence of logs to the disc drive.

14. The data storage system of claim 8 wherein the at least one first disc drive further comprises an array of disc drives.

15. The data storage system of claim 14 wherein the at least one second disc drive is formatted in such a way as to provide specific areas for mirroring the data of each one of the disc drives in the array.

16. The data storage system of claim 8 wherein the at least one second disc drive further comprises two disc drives, one disc drive for storing the logs and a second disc drive for mirroring data.

18. The log-structured block system of claim 17, wherein the header further comprises location specific information about a specific block of data.

19. The log-structured block system of claim 17, wherein the logs comprise a sequence of logs.

20. The log-structure block system of claim 17, wherein the data storage medium comprises a hard disc drive.

21. The log-structured block system of claim 17, wherein the data storage medium further comprises a writing mechanism for writing a sequence of logs as a sequential operation.

22. The log-structured block system of claim 17, wherein the data storage medium further comprises a controller enabled to reorganize the data in the logs to create an exact logical mirror of the data source based on data location information stored in the header.

24. The log-structured data writing method of claim 23, wherein the metadata comprises location specific information about a specific block of data.

25. The log-structured data writing method of claim 23, further comprising storing a sequence of logs in memory.

26. The log-structure data writing method of claim 23, wherein the data storage medium comprises a hard disc drive.

27. The log-structured data writing method of claim 23, further comprising reorganize the data in the logs to create an exact logical mirror of the data source based on data location information stored in the header.

29. The data storage system of claim 28, wherein the means for mirroring data further comprises means for creating a log-structured block system.

30. The data storage system of claim 28, wherein the means for mirroring data further comprises means for creating an exact logical mirror of the data source.

17. A log-structured block system comprising:

a source of data;

a controller, enabled to read the source of data, for creating logs containing a block of data and a header;

a memory buffer, operatively coupled to the controller, for storing the logs; and

a data storage medium, operatively coupled to the memory buffer, for writing the logs from the memory buffer, the data storage medium being a different data storage medium from where the source of data is located..

23. A log-structured data writing method, comprising steps of:

obtaining information to be stored as metadata;

creating at least one log from a data source by pairing the metadata for a specific data location with a copy of the data from the same data location;

storing the at least one log in memory; and

writing the at least one log to a data storage medium that is different than the data source.

28. A data storage system, comprising:

a controller; and

means for mirroring data based on a log-structured block system.