Locating previous versions of an object in a storage cluster

Patent metadata

Field	Value
Publication number	US-9354976-B2
Application number	US-201313791382-A
Country	US
Kind code	B2
Filing date	Mar 8, 2013
Priority date	Mar 8, 2013
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

Technology for accessing previous versions of data objects within a storage cluster including multiple storage volumes under a common namespace is disclosed herein. In some embodiments, the network storage cluster having multiple cooperative storage nodes receives a namespace identifier for a previous version of a data object. The namespace identifier includes a namespace path containing a volume junction and a time indicator indicating a point in time when the previous version of the data object existed. The network storage cluster identifies a storage volume within the network storage cluster using the volume junction. The volume junction points to a root directory of a file system of the storage volume. The network storage cluster locates, based on the namespace path, the previous version of the data object within a snapshot copy of the storage volume, wherein the snapshot copy is identified by the time indicator.

First claim

What is claimed is:

1. A method, comprising:
receiving, at a network storage cluster that includes multiple cooperative storage nodes and multiple storage volumes, a namespace identifier for a previous version of a data object, wherein the namespace identifier includes a namespace path containing a volume junction and a time indicator indicating a point in time when the previous version of the data object existed, wherein a first storage volume at a first node contains the identified volume junction as a sub-directory within a first root directory of a first file system of the first storage volume, wherein the volume junction points to a second root directory of a second file system of a second storage volume at a second node;
identifying, by a processor, the second storage volume within the network storage cluster by using the volume junction identified by the namespace identifier, wherein identifying the second storage volume within the network storage cluster by using the volume junction identified by the namespace identifier comprises:
determining, by the first file system, that the namespace path to the first file system of the first node includes a first portion identifying a first path with multiple sub-directories in the first file system and that the path includes the volume junction followed by a second portion identifying a second path with multiple sub-directories that are not in the first file system,
determining, by the second file system, that the second path includes multiple sub-directories in the second file system, and
selecting, by a namespace manager of the network storage cluster, the second storage volume based on the second portion of the namespace path lacking any volume junctions and the second file system manager determining that the second path includes multiple sub-directories in the second file system; and

locating, by the processor based on the second volume identified from the volume junction in the namespace path, the previous version of the data object within a snapshot copy of the second storage volume, wherein the snapshot copy is identified using the time indicator in the namespace identifier.

2. The method of claim 1 , wherein file systems of the storage volumes form a common namespace by including one or more volume junctions.

3. The method of claim 1 , wherein locating the previous version of the data object comprises
identifying the snapshot copy of the second file system of the second storage volume based on the time indicator, wherein the snapshot copy of the second file system includes the snapshot copy of the data object and was created at a point in time indicated by the time indicator.

4. The method of claim 1 , further comprising, prior to receiving the namespace identifier:
sending identifiers of previous versions of the data object to a client device;
receiving a message from the client device indicating a selection of one or more of the identifiers; and
sending the time indicator to the client device in response to receiving the message.

5. The method of claim 1 , further comprising:
transmitting content of the previous version of the data object to a client device.

6. The method of claim 1 , further comprising:
accessing a mapping of volume junctions to root directories; and
identifying the second root directory from the accessed mapping.

7. The method of claim 1 , further comprising:
determining that a portion of the namespace path referencing a storage volume from the first or second storage volumes includes a symbolic link to an additional data object with the storage volume; and
replacing the symbolic link within the namespace path with the additional data object to which the symbolic link points.

8. The method of claim 1 , wherein the data object is a file or a directory.

9. The method of claim 1 , wherein identifying the second storage volume within the network storage cluster by using the volume junction identified by the namespace identifier comprises:
wherein a namespace manager of the network storage cluster provides the namespace path to the first file system of the first node;
wherein the first file system provides a message to the namespace manager indicating that the volume junction points to the second root directory of the second file system;
wherein the namespace manager provides, based on receiving the message, the second portion with the second path to the second file system of the second node;
wherein the network storage cluster is independent of a client system from which a request to access the previous version of the data object is received.

10. A non-transitory machine-readable medium having stored thereon machine-executable code that, when executed by one or more machines, causes the one or more machines to:
receive, at a network storage cluster that includes multiple cooperative storage nodes and multiple storage volumes, a namespace identifier for a previous version of a data object, wherein the namespace identifier includes a namespace path containing a volume junction and a time indicator indicating a point in time when the previous version of the data object existed, wherein a first storage volume at a first node contains the volume junction identified by the namespace identifier as a sub-directory within a first root directory of a first file system of the first storage volume, wherein the volume junction points to a second root directory of a second file system of a second storage volume at a second node;
identify the second storage volume within the network storage cluster by using the volume junction identified by the namespace identifier, wherein the machine-executable code, when executed by the one or more machines, causes the one or more machines to identify the second storage volume by performing operations comprising:
determining, by the first file system, that the namespace path to the first file system of the first node includes a first portion identifying a first path with multiple sub-directories in the first file system and that the path includes the volume junction followed by a second portion identifying a second path with multiple sub-directories that are not in the first file system,
determining, by the second file system, that the second path includes multiple sub-directories in the second file system, and

selecting, by a namespace manager of the network storage cluster, the second storage volume based on the second portion of the namespace path lacking any volume junctions and the second file system manager determining that the second path includes multiple sub-directories in the second file system; and
locate, based on the identified volume junction in the namespace path, the previous version of the data object within a snapshot copy of the second storage volume, wherein the snapshot copy is identified using the time indicator in the namespace identifier.

11. The non-transitory machine-readable medium of claim 10 , wherein file systems of the storage volumes form a common namespace by including one or more volume junctions.

12. The non-transitory machine-readable medium of claim 10 , wherein the machine-executable code for locating the previous version of the data object comprises machine-executable code that, when executed by the one or more machines, causes the one or more machines to identify the snapshot copy of the second file system of the second storage volume based on the time indicator, wherein the snapshot copy of the second file system includes the snapshot copy of the data object and was created at a point in time indicated by the time indicator.

13. The non-transitory machine-readable medium of claim 10 , further co

Assignees

• Netapp Inc

Inventors

• Amlekar Shekhar A
• Mathur Ankit

Classifications

• G06F11/006 Primary

  Identification (G06F11/2289 takes precedence) · CPC title

• G06F2201/835

  Timestamp · CPC title

• G06F17/30

  Physics · mapped topic

• G06F11/1469

  Backup restoration techniques · CPC title

• G06F11/1402 Primary

  Saving, restoring, recovering or retrying · CPC title