Session sensitive data backups and restores

• US 8,082,227 B2
• Filed: 06/26/2007
• Issued: 12/20/2011
• Est. Priority Date: 10/10/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Balakrishnan, Kalidas, Ranganathan, Shyamsundar
• Primary Examiner(s): Breene, John E
• Assistant Examiner(s): Kerzhner, Aleksandr
• Application Number:
  US11/821,841
• Publication Number:
  US 20080086518A1
• Time in Patent Office: 1,638 Days
• Field of Search: 707/640, 707/999.204
• US Class Current: 707/640
• 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 11/1464 for networked environments
• CPC Class Codes: G06F 11/1469 Backup restoration techniques

Abstract

Techniques for the session sensitive data backups and restores are presented. Data having a plurality of hard linked file references are backed up and restored once during a backup operation. Any modifications to the backed up data are noted as session-specific versions and also backed up once. The hard linked file references are maintained in a data structure and managed during backups to define associations to the backed up data and to the session-specific versions of the data. The data structure is also used during restores to re-establish desired hard linked file reference associations to either the backed up data or to a particular session-specific versions of the data.

Claims

1. A method, comprising:

initiating a backup operation;

detecting a first hard link for primary data and a second hard link for the primary data and backing up the first and second hard links within a link data structure associated with the backup operation and backing up the primary data once; and

encountering a third hard link for a modified version of the primary data during the backup operation and backing up the third hard link within the data structure and backing up the modified version of the primary data as a session-specific version of the primary data by describing changes of the modified version in metadata and using the metadata as the session-specific version of the primary data, the metadata represents the primary data that is altered via the changes during the backup operation and before the backup operation has a chance to conclude, the link data structure includes a same identifier for the primary data and the modified version of the primary data, the same identifier stored in an single entry within the linked data structure and the entry includes a list of additional information including the first hard link, the second hard link, and the third hard link, the third hard link including a pointer to the metadata, the linked data structure includes hashed entries, each hashed entry representing particular primary data as a chain of additional data structures, and each additional data structure having;

a particular identifier for the particular primary data, a particular file system identifier for a file system of the particular primary data, a link count that identifies a total number of links that point to a particular hard link for the hashed entry, and a next pointer for a next additional data structure in the chain for the hashed entry.

2. The method of claim 1 further comprising, maintaining one or more additional hard links within the link data structure for the primary data, for the session-specific version, for other session-specific versions of the primary data, and for other primary data.

3. The method of claim 2 further comprising, including a first pointer in the link data structure that references the primary data and including a second pointer in the link data structure that references the modified version of the primary data.

4. The method of claim 1, wherein detecting further includes recognizing that the second hard link has a changed time but that a size and a modify date and time for the primary data are unchanged from that which is associated with the first hard link.

5. The method of claim 1, wherein encountering further includes noting differences, within a backup structure during the backup operation, for the modified version in relation to differences with the primary data and recording the differences as the modified version within the backup structure.

6. The method of claim 1, wherein initiating further includes recognizing the backup operation as a full backup of storage or as an incremental backup of storage.

7. A method, comprising:

initiating a restore operation;

encountering primary data in backup data and restoring the primary data;

detecting a session-specific version of the primary data in the backup data and restoring the session-specific version, the session-specific version of the primary data representing an altered version of the primary data that occurred during a backup operation and before the backup operation had a chance to conclude, the session-specific version represented as changes to the primary data defined in metadata that can be applied to the primary data to arrive at the session specific version; and

noting first, second, and third hard links in the backup data and updating a link table, wherein the first, second, third hard links reference the primary data and the session-specific version of the primary data as one entry in the link table using a same identifier for the primary data and the session-specific data, the one entry includes a list having the first hard link, the second hard link, and the third hard link, and the third hard link having a pointer to the metadata, the linked table includes hashed entries, each hashed entry representing particular primary data as a chain of additional data structures, and each additional data structure having;

a particular identifier for the particular primary data, a particular file system identifier for a file system of the particular primary data, a link count that identifies a total number of links that point to a particular hard link for the hashed entry, and a next pointer for a next additional data structure in the chain for the hashed entry.

8. The method of claim 7 further comprising:

restoring the first, second, and third hard links from the link table; and

linking the first, second, and third hard links to the primary data or to the session-specific version of the primary data.

9. The method of claim 8, wherein restoring further includes issuing one or more operating system commands to link the first, second, and third hard links to the primary data or to the session-specific version of the primary data.

10. The method of claim 7, wherein initiating the restore operation further includes recognizing the restore operation as a full restore operation or an incremental restore operation.

11. The method of claim 7, wherein noting further includes acquiring the first, second, and third hard links from a link data structure associated with the primary data within the backup data and created during the backup operation.

12. The method of claim 11 further comprising:

recognizing from the link data structure that the first, second, and third hard links are associated with both the primary data and the session-specific version of the primary data; and

permitting a user to select between linking the first, second, and third hard links to the primary data or linking the first, second, and third hard links to the session-specific version of the primary data for restoration during the restore operation.

13. A system, comprising:

a link network structure; and

a session-sensitive backup service, the session-sensitive backup service is to build the link network structure by representing first hard links directed to primary data detected in storage during a backup operation and by representing at least one second hard link directed to a session-specific version of the primary data, the session-specific version represented as metadata defining changes that when applied to the primary data provides the session-specific version, and the session-sensitive backup service is to backup the primary data once and independent of a total number of first hard links and is to backup the session-specific version of the primary data, via the metadata, and independent of a total number of second hard links, the session-specific version representing the primary data altered during the backup operation and before the backup operation concludes and defined by the metadata, the link data structure include a single identifier and entry for the primary data and the session-specific version of the primary data, the entry including a list having the first hard links and the second hard links and the second hard links including pointers to the metadata, the linked data structure includes hashed entries, each hashed entry representing particular primary data as a chain of additional data structures, and each additional data structure having;

a particular identifier for the particular primary data, a particular file system identifier for a file system of the particular primary data, a link count that identifies a total number of links that point to a particular hard link for the hashed entry, and a next pointer for a next additional data structure in the chain for the hashed entry.

14. The system of claim 13, wherein the session-sensitive backup service is to index the link network structure by a same iNode number associated with both the primary data and the session-specific version of the primary data.

15. The system of claim 13, wherein the session-sensitive backup service detects the session-specific version and the second hard link as being generated within storage after the backup operation commences but before it concludes.

16. The system of claim 13, wherein the session-sensitive backup service adds third hard links within the link network structure, wherein the third hard links are associated with other primary data detected during the backup operation.

17. A system, comprising:

a session-sensitive backup service; and

a session-sensitive restore service, the session-sensitive backup service maintains first hard links to primary data and second hard links to a session-specific version of the primary data during a backup operation and backs up the primary data and the session-specific version of the primary data just once during the backup operation, the session-specific version represented as metadata defining changes that when applied to the primary data provides the session-specific version, and the session-sensitive restore service restores the primary data or of the session-specific version of the primary data during a restore operation, by applying the changes defined in the metadata to the primary data, and the session-sensitive restore service enables the first and second hard links to be associated with the primary data or enables the first and second hard links to be associated with the session-specific version of the primary data, the session-specific version represents the primary data altered during the backup operation and before the backup operation concludes, the session-sensitive backup service creates a backup data structure where the primary data and the session-specific version are identified via a same identifier and within a single entry in the data backup structure, the single entry including a list for the first hard links and the second hard links and the second hard links including pointers to the metadata, and the session-sensitive restore service uses the backup data structure during the restore operation, the data backup structure includes hashed entries, each hashed entry representing particular primary data as a chain of additional data structures, and each additional data structure having;

a particular identifier for the particular primary data, a particular file system identifier for a file system of the particular primary data, a link count that identifies a total number of links that point to a particular hard link for the hashed entry, and a next pointer for a next additional data structure in the chain for the hashed entry.

18. The system of claim 17 further comprising, a link data structure, wherein the link data structure is generated and managed by the session-sensitive backup service to house the first hard links and the second hard links and their associations with the primary data and the session-specific version of the primary data.

19. The system of claim 18, wherein the session-sensitive restore service uses the link data structure during the restore operation to identify the first hard links and the second hard links and their associations to the primary data and the session-specific versions of the primary data.

20. The system of claim 17 further comprising, a link table, wherein the session-sensitive restore service notes the associations between the first, second, and third hard links to the primary data and the session-specific version of the primary data, and wherein the session-sensitive restore service uses the link table to request an operating system to establish the associations to either the primary data or the session-specific version of the primary data to complete the restore operation.

21. The system of claim 17, wherein the backup operation can be a full backup operation or an incremental backup operation.

22. The system of claim 17, wherein the restore operation can be a full restore operation or an incremental restore operation.