Methods and Apparatuses for Data Protection

• US 20100114847A1
• Filed: 10/29/2009
• Published: 05/06/2010
• Est. Priority Date: 06/10/2005
• Status: Active Grant

• Current Assignee: Dominic Benjamin Giampaolo, Michael Steven Mackovitch
• Original Assignee: Dominic Benjamin Giampaolo, Michael Steven Mackovitch
• Inventors: Mackovitch, Michael Steven, Giampaolo, Dominic Benjamin
• Granted Patent: US 8,239,356 B2
• Time in Patent Office: Days
• US Class Current: 707/695
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: G06F 11/1474 in transactions G06F16/20 takes precedence
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

Methods and apparatuses for data protection against corrupted write operations. In one embodiment, a technique of crash protection uses an atomically updated global transaction indicator to switch a set of data structures from one set of versions to another set. In one embodiment, the storage space for multiple versions of a data structure is allocated at the time the data structure is created on the storage device so that the multiple versions of the data structure can be kept close by. Between two consistent points, some data structures are modified to create new versions without changing the corresponding previous versions; and unmodified data structures are not copied. At a consistent point, the global transaction indicator is updated to indicate a set of consistent versions of the data structures, such as metadata of a file system.

Claims

1. A machine readable medium containing executable computer program instructions which when executed by a data processing system cause said system to perform a method for processing data, the method comprising:

after a crash, retrieving a global transaction identifier; and

storing information indicating one or more transaction identifiers as invalid according to the global transaction ID.

2. The medium of claim 1, wherein the method further comprises:

receiving a request to access a first data;

determining whether or not a version of the first data is invalid based one checking a transaction identifier of the version of the first data against at least the information indicating the one or more transaction identifiers as invalid.

3. The medium of claim 2, wherein the global transaction identifier is retrieved from a storage device where a plurality of versions of the first data are stored;

and the information indicating the one or more transaction identifiers as invalid is stored onto the storage device; and

the method further comprises;

updating the global transaction identifier before providing a transaction identifier to record a new version of data onto the storage device.

4. The medium of claim 2, wherein the method further comprises:

retaining at least a latest version of each data which is part of a latest consistent point that is indicated by the global transaction ID.

5. A machine readable medium containing executable computer program instructions which when executed by a data processing system cause said system to perform a method for processing data, the method comprising:

after a crash, retrieving information indicating one or more locations in a storage device;

retrieving a global transaction ID; and

searching the one or more locations in the storage device according to the information for one or more invalid versions of data based on checking whether or not a relation between a transaction identifier of a version of data and the global transaction ID is broken.

6. The medium of claim 5, wherein the method further comprises:

deleting one or more versions of data with invalid transaction identifiers;

wherein a transaction identifier larger than the global transaction ID is invalid.

7. The medium of claim 5, wherein the information and the global transaction ID are retrieved from the storage device;

a file system records the information indicating locations of new versions of data into the storage device before recording corresponding new versions; and

the file system updates atomically the global transaction ID on the storage device upon completion of recording the corresponding new versions.

8. The medium of claim 5, wherein the method further comprises:

retaining at least a latest version of each data which is part of a latest consistent point that is indicated by the global transaction ID.

9. A method for processing data, the method comprising:

after a crash, retrieving a global transaction identifier; and

storing information indicating one or more transaction identifiers as invalid according to the global transaction ID.

10. The method of claim 9, further comprising:

updating the global transaction identifier before providing a transaction identifier to record a new version of data onto the storage device;

receiving a request to access a first data; and

determining whether or not a version of the first data is invalid based one checking a transaction identifier of the version of the first data against at least the information indicating the one or more transaction identifiers as invalid.

11. The method of claim 10, wherein the global transaction identifier is retrieved from a storage device where a plurality of versions of the first data are stored;

and the information indicating the one or more transaction identifiers as invalid is stored onto the storage device.

12. A method for processing data, the method comprising:

after a crash, retrieving information indicating one or more locations in a storage device;

retrieving a global transaction ID; and

searching the one or more locations in the storage device according to the information for one or more invalid versions of data based on checking whether or not a relation between a transaction identifier of a version of data and the global transaction ID is broken.

13. The method of claim 12, further comprising:

deleting one or more versions of data with invalid transaction identifiers;

wherein a transaction identifier larger than the global transaction ID is invalid.

14. The method of claim 12, wherein the information and the global transaction ID are retrieved from the storage device;

a file system records the information indicating locations of new versions of data into the storage device before recording corresponding new versions; and

the file system updates atomically the global transaction ID on the storage device upon completion of recording the corresponding new versions.

15. A device, comprising:

means for, after a crash, retrieving a global transaction identifier; and

means for storing information indicating one or more transaction identifiers as invalid according to the global transaction ID.

16. A device, comprising:

means for, after a crash, retrieving information indicating one or more locations in a non-volatile portion of the device;

means for retrieving a global transaction ID; and

means for searching the one or more locations in the non-volatile portion of the device according to the information for one or more invalid versions of data based on checking whether or not a relation between a transaction identifier of a version of data and the global transaction ID is broken.