Detecting and managing missing parents between primary and secondary data stores

• US 7,603,397 B1
• Filed: 10/03/2006
• Issued: 10/13/2009
• Est. Priority Date: 10/03/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Tinius, Paul E., Hutchinson, Thomas Dixon, Hagerstrom, Carl F., Bharthulwar, Shridhar
• Primary Examiner(s): Trujillo; James
• Assistant Examiner(s): PHILLIPS, III, ALBERT M
• Application Number:
  US11/538,316
• Time in Patent Office: 1,106 Days
• Field of Search: 707/204
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 16/1744 using compression, e.g. sparse files
• CPC Class Codes: G06F 16/185 Hierarchical storage management [HSM] systems, e.g. file migration or policies thereof details of archiving G06F16/11
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A method and system for locating and/or eliminating missing parent files within a primary storage device. The method includes identifying a placeholder file on a primary storage device, the placeholder file having an offline reference and being associated with file identification data, identifying a secondary file on a secondary storage device using data in the offline reference of the placeholder file, identifying an online reference of the secondary file, determining if the online reference of the secondary file properly references the file identification data of the placeholder file, and updating the online reference of the secondary file so that it includes the file identification data of the placeholder file.

Claims

1. In a distributed computing system having a primary storage device, a secondary storage device and a policy engine server, the policy engine server being configured to manage migration of files between the primary and secondary storage devices by migrating data files on the primary storage device to the secondary storage device and replacing the data files on the primary storage device with a placeholder files, a method for locating placeholder files within the primary storage device that are not properly referenced by secondary files stored on the secondary storage device, the method comprising:

identifying a placeholder file stored on the primary storage device, the placeholder file including an offline reference to a secondary file stored on the secondary storage device, wherein the offline reference includes an address of the secondary file;

identifying the secondary file stored on secondary storage device and referenced by the address of the secondary file in the offline reference included in the placeholder file;

identifying an online reference included in the secondary file, wherein the online reference includes an address to a particular placeholder file on the primary storage device;

determining that the placeholder file is a missing parent file if the address to the particular placeholder file is not to the placeholder file; and

updating the online reference of the secondary file to include the file identification data of the placeholder file to properly identify the placeholder file.

2. The method as recited in claim 1, further comprising at least one of:

notifying a user of the policy engine server if the online reference of the secondary file does not properly reference the file identification data of the placeholder file and indicating the reason for the improper reference.

3. The method as recited in claim 1, wherein the primary storage device is further configured to communicate with a client computer system, the client computer system able to access the secondary file via the placeholder file on the primary storage device.

4. The method as recited in claim 2, wherein the file identification data of the placeholder file includes a filename that has been renamed, and wherein the online reference of the secondary file is updated to include the renamed filename of the placeholder file.

5. The method as recited in claim 2, wherein the file identification data of the placeholder file includes an additional filename, and wherein the online reference of the secondary file is updated to include the additional filename of the placeholder file.

6. The method as recited in claim 2, wherein the placeholder file has been restored from a backup location to a different location in a file system of the primary storage device than a previous placeholder file such that new file identification data of the placeholder file is created, and wherein the online reference of the secondary file is updated to include the new file identification data of the placeholder file.

7. The method as recited in claim 1, wherein the online reference of the secondary file includes a content address of the placeholder file.

8. A location addressable data migration storage system for managing placeholder files that are not properly referenced by secondary files, the system comprising:

a primary storage device employing one of location addressable storage or content addressable storage to store data files and configured to store and detect a placeholder file in the place of a data file when the data file is migrated and stored as a secondary file on a secondary storage device, the detected placeholder file including an offline reference for identifying the secondary file, and the detected placeholder file being associated with file identification data for identifying the detected placeholder file;

the secondary storage device employing one of location addressable storage or content addressable storage and configured to store the secondary file, the secondary file being associated with file identification data for identifying the secondary file, the file identification data of the secondary file relating to the offline reference of the detected placeholder file, and the secondary file including at least one online reference to a referenced placeholder file stored on the primary storage device; and

a policy engine server including a file management module for detecting that the detected placeholder file is not properly identified by the at least one online reference of the secondary file, wherein the detected placeholder file is a missing parent file when not properly identified by the at least one online reference, wherein the policy engine server eliminates the detected placeholder file or updates at least one online reference of the secondary file such that the online reference refers to the detected placeholder file.

9. The system as recited in claim 8, wherein the file management module of the policy engine server is further configured for performing at least one of:

notifying a user of the policy engine server that the detected placeholder file is not properly identified by the at least one online reference of the secondary file.

10. The system as recited in claim 8, wherein prior to updating the at least one online reference of the secondary file such that the online reference refers to the detected placeholder file, the file identification data of the detected placeholder file included at least one of a renamed filename, an added filename, or new file identification data from the detected placeholder file being restored from a backup location to a different location in a file system of the primary storage device than a previous placeholder file.

11. The system as recited in claim 8, wherein the file identification data of the secondary file further includes one or more filenames associated with the detected placeholder file.

12. The system as recited in claim 8, wherein the policy engine server further includes a data migration module for moving files between the primary storage device and the secondary storage device, the data migration module configured to delete a data file from the primary storage device, create the detected placeholder file to represent the deleted data file, and copy the data file to the secondary storage device in the form of the secondary file.

13. The system as recited in claim 8, further comprising a client computer system configured to access the placeholder file from the primary storage device and access the secondary file via the placeholder file.

14. In a distributed computer having a primary storage device, a secondary storage device and a policy engine server, the policy engine server being configured to manage migration of files between the primary storage device and the secondary storage device, wherein a data file on the primary storage device is replaced with a placeholder file and the data file is stored on the secondary storage device as a secondary file, a computer program product configured to implement a method of locating and eliminating missing parent files within the primary storage device, the computer program product comprising one or more computer readable media having stored thereon computer executable instructions that, when executed by a processor, cause the policy engine server to perform the following:

identify a placeholder file stored on the primary storage device, the placeholder file having an offline reference to a secondary file stored on the secondary storage device and file identification data, wherein the offline reference includes an address to the secondary file;

identify the secondary file stored on a secondary storage device using the offline reference of the placeholder file;

identify an online reference included in the secondary file;

determine that the placeholder file is a missing parent if the online reference does not properly identify the placeholder file; and

notify a user of the policy engine server that the online reference of the secondary file does not properly reference the file identification data of the placeholder file.

15. The method as recited in claim 14, wherein the computer executable instructions that cause the server system to identify a secondary file on a secondary storage device using the offline reference of the placeholder file further comprise instructions to cause the policy engine server to perform at least one of the following:

indicate the reason for the improper reference;

or

update the online reference of the secondary file so that it includes the file identification data of the placeholder file or eliminate the placeholder file from the primary storage device.

16. The method as recited in claim 14, wherein the file identification data of the placeholder file includes a filename that has been renamed, and wherein the online reference of the secondary file is updated to include the renamed filename of the placeholder file.

17. The method as recited in claim 14, wherein the file identification data of the placeholder file includes an additional filename, and wherein the online reference of the secondary file is updated to include the additional filename of the placeholder file.

18. The method as recited in claim 14, wherein the placeholder file has been restored from a backup location such that new file identification data of the placeholder file is created, and wherein the online reference of the secondary file is updated to include the new file identification data of the placeholder file.