Versioned file system with fast restore

• US 20120054156A1
• Filed: 08/30/2010
• Published: 03/01/2012
• Est. Priority Date: 08/30/2010
• Status: Active Grant

• Current Assignee: Nasuni Corporation
• Original Assignee: Nasuni Corporation
• Inventors: Mason, Robert S. Jr., Shaw, David M., Fridella, Stephen, Baughman, Kevin W.
• Granted Patent: US 8,799,231 B2
• Time in Patent Office: Days
• US Class Current: 707/679
• CPC Class Codes: G06F 11/1448 Management of the data involved in backup or backup restore
• CPC Class Codes: G06F 16/1873 Versioning file systems, temporal file systems, e.g. file system supporting different historic versions of files

Abstract

A versioned file system comprises a set of structured data representations, such as XML. Each structured data representation corresponds to a “version,” and each version comprises a tree of write-once objects rooted at a root directory manifest. Each version in the versioned file system has associated therewith a “borrow window.” When it is desired to reconstruct the file system to a point in time (or, more generally, a given state), i.e., to perform a “restore,” it is only required to walk (use) a single structured data representation (a tree). During a restore, metadata is pulled back from the cloud first, so users can see the existence of needed files immediately. The remainder of the data is then pulled back from the cloud if/when the user goes to open the file. As a result, the entire file system (or any portion thereof) can be restored to a previous time nearly instantaneously. A “fast” restore is performed if an object being restored exists within a “borrow window” of the version from which the system is restoring.

Claims

1. A computer-readable medium having stored thereon instructions that, when executed by a processor, perform a method associated with a versioned file system comprising a set of versions, wherein each version comprises a tree of write-once objects rooted at a root directory manifest, and wherein versions may share objects, a method comprising:

associating a borrow window to each of a set of versions in the versioned file system;

in response to a request to restore a file from a version in the versioned file system, determining whether the file exists within a borrow window of the version; and

if the file exists within the borrow window of the version, returning metadata associated with the file so that the file has an appearance of being restored; and

upon receipt of a request to open the file, returning contents of the file.

2. The medium as described in claim 1 wherein the borrow window of a first version differs from a borrow window of a second version.

3. The medium as described in claim 1 wherein upon determining that the file exists within the borrow window of the version, the method includes associating the file with a new location in the versioned file system, where the association results in first and second identifiers within the versioned file system pointing to the file.

4. The medium as described in claim 1 wherein the file is one of:

a file, and a portion of a file.

5. The medium as described in claim 1 wherein the request is initiated from a web-based interface.

6. Apparatus, comprising:

a processor;

computer memory holding computer program instructions that when executed by the processor perform a method associated with a versioned file system, the versioned file system comprising a set of versions, wherein each version comprises a tree of write-once objects rooted at a root directory manifest, and wherein each version has an associated borrow window, the method comprising;

associating a borrow window to each of a set of versions in the versioned file system;

in response to a request to restore a file from a version in the versioned file system, determining whether the file exists within a borrow window of the version; and

if the file exists within the borrow window of the version, returning metadata associated with the file so that the file has an appearance of being restored; and

upon receipt of a request to open the file, returning contents of the file.

7. The apparatus as described in claim 6 wherein a borrow window of a first version differs from the borrow window of a second version.

8. The apparatus as described in claim 6 wherein upon determining that the file exists within the borrow window of the version, the method includes associating the file with a new location in the versioned file system, where the association results in first and second identifiers within the versioned file system pointing to the file.

9. The apparatus as described in claim 6 wherein the file is one of:

a file, and a portion of a file.

10. The apparatus as described in claim 6 further including a web-based interface from which the request is initiated.