IMPLEMENTING READ/WRITE, MULTI-VERSIONED FILE SYSTEM ON TOP OF BACKUP DATA

• US 20080243953A1
• Filed: 03/30/2007
• Published: 10/02/2008
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Wu, Weibao, Zeis, Mike, Hartnett, Tom
• Granted Patent: US 8,489,830 B2
• Time in Patent Office: Days
• US Class Current: 707/204
• CPC Class Codes: G06F 11/1448 Management of the data involved in backup or backup restore
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 16/1752 based on file chunks

Abstract

Various embodiments of a computer system and methods are disclosed. In one embodiment, a computer system includes hosts coupled to a backup medium. The backup medium stores data segments and objects, each object referencing one or more segments. A second host conveys a write request to a first host identifying a data entity comprising segments referenced by a first object. The first host restores a copy of the data entity and creates a second object referencing the segments that were referenced by the first object in response to receiving the write request. The first host adds segment references to the second object in response to receiving a change that adds data to the copy or deletes a portion of a segment from the copy. The first host removes a segment reference from the second object if a change deletes all of a segment from the copy.

Claims

1. A computer system comprising:

a first host coupled to a backup medium configured to store a plurality of backup data objects and a plurality of data segments, each data object referencing one or more of the plurality of data segments; and

a second host configured to;

convey to the first host a write request that identifies a data entity, wherein the data entity comprises data segments referenced by a first data object of the plurality of backup data objects;

convey to the first host data changes indicative of modifications to the data entity;

wherein in response to the write request, the first host is configured to;

restore a copy of the data entity; and

create a second data object that references the data segments referenced by the first data object; and

wherein the first host is further configured to;

add one or more data segment references to the second data object, in response to receiving a data change that adds data to the copy or deletes a portion of a data segment from the copy; and

remove a data segment reference from the second data object if a data change deletes all of a data segment from the copy.

2. The system as recited in claim 1, wherein the backup medium comprises single instance backup data.

3. The system as recited in claim 1, further comprising a catalog configured to store metadata describing the plurality of backup data objects.

4. The system as recited in claim 3, wherein the second host is further configured to access the backup medium through a virtual file system interface.

5. The system as recited in claim 4, wherein the virtual file system interface is configured to enable the second host to write data objects to the backup medium.

6. The system as recited in claim 4, wherein the virtual file system interface is configured to enable the second host to create and store multiple versions of backup data objects on the backup medium.

7. The system as recited in claim 6, wherein the catalog is further configured to store metadata describing branches containing multiple version of the plurality of backup data objects.

8. A method for accessing backup data, the method comprising:

storing a plurality of backup data objects and a plurality of data segments on a backup medium, each data object referencing one or more of the plurality of data segments; and

receiving a write request identifying a data entity, wherein the data entity comprises data segments referenced by a first data object of the plurality of backup data objects;

restoring a copy of the data entity and creating a second data object that references the data segments referenced by the first data object, in response to the write request;

receiving data changes indicative of modifications to the data entity;

adding one or more data segment references to the second data object in response to receiving a data change that adds data to the copy or deletes a portion of a data segment from the copy;

removing a data segment reference from the second data object if a data change deletes all of a data segment from the copy.

9. The method as recited in claim 8, wherein the backup medium comprises single instance backup data.

10. The method as recited in claim 8, further comprising storing metadata describing the plurality of backup data objects in a catalog.

11. The method as recited in claim 10, further comprising accessing the backup medium through a virtual file system interface.

12. The method as recited in claim 11, further comprising writing data objects to the backup medium through the virtual file system interface

13. The system as recited in claim 11, further comprising creating and storing multiple versions of backup data objects on the backup medium through the virtual file system.

14. The method as recited in claim 13, further comprising storing metadata describing branches containing multiple version of the plurality of backup data objects in the catalog.

15. A plurality of computer readable media storing computer instructions that are executable by a processor to:

store a plurality of backup data objects and a plurality of data segments on a backup medium, each data object referencing one or more of the plurality of data segments;

receive a write request identifying a data entity, wherein the data entity comprises data segments referenced by a first data object of the plurality of backup data objects;

restore a copy of the data entity and create a second data object that references the data segments referenced by the first data object, in response to the write request;

receive data changes indicative of modifications to the data entity;

add one or more data segment references to the second data object in response to receiving a data change that adds data to the copy or deletes a portion of a data segment from the copy;

remove a data segment reference from the second data object if a data change deletes all of a data segment from the copy.

16. The computer readable medium as recited in claim 15, wherein the backup medium comprises single instance backup data.

17. The computer readable medium as recited in claim 15, wherein the instructions are further executable to store metadata describing the plurality of backup data objects in a catalog.

18. The computer readable medium as recited in claim 17, wherein the instructions are further executable to access the backup medium through a virtual file system interface.

19. The computer readable medium as recited in claim 17, wherein the instructions are further executable to write data objects to the backup medium through the virtual file system interface

20. The computer readable medium as recited in claim 17, wherein the instructions are further executable to create and store multiple versions of backup data objects on the backup medium through the virtual file system.