Recovering a file system to any point-in-time in the past with guaranteed structure, content consistency and integrity

• US 20080256138A1
• Filed: 03/31/2008
• Published: 10/16/2008
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Quest Software, Inc.
• Original Assignee: Quest Software, Inc.
• Inventors: Sim-Tang, Siew Yong
• Granted Patent: US 8,131,723 B2
• Time in Patent Office: Days
• US Class Current: 707/202
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• 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 16/1873 Versioning file systems, temporal file systems, e.g. file system supporting different historic versions of files

Abstract

A data management system (DMS) includes a continuous real-time object store that captures all real-time activities, with associated object metadata information. The DMS is capable of reintroducing any point-in-time view of data ranging from a granular object to an entire file system. A set of algorithms (for creation of a file or directory, modification of a file or directory, deletion of a file or directory, and relocation/renaming of a file or directory) are used to generate and maintain a file system history in the DMS and to ensure that a latest version of a directory always refers to a latest version of its children until the directory changed. Any point-in-time recovery is implemented using the file system history in one of various ways to provide strong individual file integrity, exact point-in-time crash consistency, and/or recovery of last version of all files in the file system.

Claims

1. A data management method, comprising:

storing a real-time history of a file system as a logical representation; and

using the logical representation for any point-in-time recovery of the file system.

2. The method as described in claim 1 wherein the any point-in-time recovery provides integrity recovery of an individual file in the file system.

3. The method as described in claim 2 wherein integrity recovery provides, at a recovery point, a latest version of the individual file prior that is consistent.

4. The method as described in claim 1 wherein the any point-in-time recovery provides substantially exact point-in-time crash consistency recovery.

5. The method as described in claim 4 wherein exact point-in-time crash consistency constructs an image of the file system at a recovery point by obtaining a latest version and applying changes after the latest version and up to the recovery point.

6. The method as described in claim 1 wherein the any point-in-time recovery of the file system provides last version of all files in the file system.

7. The method as described in claim 6 wherein last version of all files in the file system recovers all files up to a latest version regardless of whether a state of a given file is consistent or suspect.

8. The method of claim 1 wherein the step of storing the real-time history includes:

generating a data structure, comprising;

a set of data objects each of which conform to an object hierarchy, at least first and second of the data objects being associated with one another and representing a first version of a file system component and a subsequent version of the file system component, the file system component being one of;

a directory, and a file; and

a set of links associating the set of data objects, wherein the set of links comprise at least one version link associating the first version of the file system component and the subsequent version of the file system component;

wherein the set of data objects and the set of links provide an n-dimensional logical representation of the file system component at a given point-in-time.

9. The method as described in claim 1 further including:

transferring the real-time history from a first location to a second location remote from the first location.

10. The method as described in claim 9 wherein the real-time history provides one of:

a data protection service, and a data distribution service,

11. The method as described in claim 1 wherein recovery of the file system includes recovery of one of:

a file, a sub-directory, a file system volume, and a set of files that belong to a database.

12. The method as described in claim 11 wherein the set of files that belong to the database span one or more volumes.

13. The method as described in claim 1 further including extracting an audit trail from the file system identifying, for a given object, a change and an identifier associated with a user who initiated the change.

14. The method as described in claim 8 wherein a given version is associated with an event.

15. The method as described in claim 14 wherein the event is one of:

an application checkpoint, a user checkpoint, and a system event.