FILE SYSTEM BACKUP USING CHANGE JOURNAL

• US 20120143825A1
• Filed: 12/03/2010
• Published: 06/07/2012
• Est. Priority Date: 12/03/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Doshi, Apurva Ashwin, Lyakhovitskiy, Grigory Borisovich, Havewala, Sarosh Cyrus, Boehm, Branton Nicolas, Pang, Juan-Lee
• Granted Patent: US 9,824,091 B2
• Time in Patent Office: Days
• US Class Current: 707/648
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 16/113 Details of archiving lifecycle management in storage systems G06F3/0649; backup systems G06F11/1446
• CPC Class Codes: G06F 16/128 Details of file system snapshots on the file-level, e.g. snapshot creation, administration, deletion use of snapshots for error detection or correction G06F11/14, G06F11/16
• CPC Class Codes: G06F 16/1734 Details of monitoring file system events, e.g. by the use of hooks, filter drivers, logs
• CPC Class Codes: G06F 16/1815 Journaling file systems
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

Aspects of the subject matter described herein relate to backups and change journals. In aspects, a change journal is read to determine changes that have occurred to objects of a file system. From these changes a data structure is created to capture path information and collect changes for each object. Where the data structure is insufficient to identify a complete path, the live file system is consulted. After the data structure is complete, a data protection engine uses the data structure to update a catalog at least to provide the capability to view the namespace of the protected objects at one or more times covered by the catalog.

Claims

1. A method implemented at least in part by a computer, the method comprising:

opening a change journal that includes records that indicate file system objects that have changed, the file system objects included in a file system;

reading the change journal potentially in parallel with additional records being written to the change journal;

updating a data structure that indicates paths of the file system objects that have changed;

if a file system object reflected in the data structure changed after reading the change journal, reading more of the change journal potentially in parallel with additional records being written to the change journal and updating the data structure in accordance with the additional records; and

updating a catalog using the data structure, the catalog usable to construct a namespace of the file system that existed at a backup set time covered by the catalog, the namespace indicating files and directories that existed in the file system at the backup set time.

2. The method of claim 1, wherein each of the records includes name information of a changed file system object and a parent thereof, the name information not including either a complete path of the changed file system object or a complete path of the parent thereof.

3. The method of claim 1, wherein each record is associated with a number that indicates a sequence of the record in the change journal.

4. The method of claim 3, further comprising determining if a file system object reflected in the data structure changed after reading the change journal by comparing a sequence number of the file system object with a last read sequence number of the change journal.

5. The method of claim 1, wherein updating the data structure comprises, for a record of the change journal, reading a file name of a file associated with the record, reading a sequence number of the file, reading an identifier of a parent of the file, and putting the file name, sequence number, and identifier in a child node of the data structure.

6. The method of claim 5, further comprising if a parent node for the parent does not exist in the data structure, creating the parent node and inserting link data into the parent node to identify the child node.

7. The method of claim 5, further comprising if the parent node for the parent does exist in the data structure, updating the data structure to indicate that the child node is a child of the parent node.

8. The method of claim 1, wherein updating the catalog comprises updating a timestamp in the catalog for a file system object that has successfully been backed up to a backup target, the timestamp indicating a last visible time of the file system object.

9. A computer storage medium having computer-executable instructions, which when executed perform actions, comprising:

receiving a change record that indicates a change that has happened to a file system object of a file system;

if the file system object was changed but not moved, performing actions, comprising;

creating a first namespace record for the file system object,

creating a new file record for the file system object, and

linking the first namespace record to the new file record;

if the file system object was moved but not changed, performing actions, comprising;

creating a second namespace record for the file system object, and

linking the second namespace record to a previous file record that represented the file system object, the previous file record existing prior to the receiving the change record.

10. The computer storage medium of claim 9, further comprising attempting to create a backup copy of the file system object and if successful, updating a prior namespace record to indicate that the prior namespace record is no longer visible in a current namespace.

11. The computer storage medium of claim 9, further comprising attempting to create a backup copy of the file system object and if unsuccessful, deleting the first namespace record.

12. The computer storage medium of claim 9, further comprising if the file system object was moved but not changed, updating a prior namespace record to indicate that the prior namespace record is no longer visible in a current namespace.

13. The computer storage medium of claim 9, further comprising if the change record indicates that the file system object was deleted, updating a prior namespace record with a value that indicates a deletion time of the file system object.

14. The computer storage medium of claim 13, wherein updating the prior namespace record with a value that indicates a deletion time of the file system object causes the namespace record to be no longer visible in a current namespace.

15. The computer storage medium of claim 9, wherein if the change record indicates that the file system object was added, then creating a namespace record for the file system object, creating a file record for the file system object, and indicating that the namespace record is visible in a current namespace.

16. In a computing environment, a system, comprising:

a change detector operable to open a change journal of a file system and read records of the change journal potentially in parallel with additional records being written to the change journal, the change detector further operable to create a data structure that indicates paths of the file system objects that have changed;

a catalog manager operable to provide access to a catalog, the catalog including a namespace table and a file table, the namespace table indicating files and directories that existed on the file system as well as times at which the files and directories existed; and

a data protection engine operable to obtain change data records from the change detector, each change data record identifying a file system object and a change that occurred to the file system object, the data protection engine further operable to use the catalog manager to update the catalog to maintain the namespace table.

17. The system of claim 16, wherein the data protection engine being operable to use the catalog manager to update the catalog to maintain the namespace table comprises the data protection engine being operable to instruct the catalog manager to indicate in the namespace table that a file system object has been deleted as of a particular backup set identifier.

18. The system of claim 16, wherein the data protection engine being operable to use the catalog manager to update the catalog to maintain the namespace table comprises the data protection engine being operable to instruct the catalog manager to indicate in the namespace table that a file system object is no longer visible in a current namespace.

19. The system of claim 16, wherein the data protection engine being operable to use the catalog manager to update the catalog to maintain the namespace table comprises the data protection engine being operable to instruct the catalog manager to create a new file record in a file table and a new namespace record in the namespace table, the new namespace record indicating a new version of a changed file system object the new file record including backup data that includes backup status of the changed file system object.

20. The system of claim 16, wherein the data protection engine is further operable to use the catalog in backing up file system objects that have changed.