Using a snapshot as a data source

• US 8,959,299 B2
• Filed: 09/14/2009
• Issued: 02/17/2015
• Est. Priority Date: 11/15/2004
• Status: Active Grant

• Current Assignee: CommVault Systems Incorporated
• Original Assignee: CommVault Systems Incorporated
• Inventors: Ngo, David, Prahlad, Anand, Gokhale, Parag, Pawar, Rahul S.
• Primary Examiner(s): MACKALL, LARRY T
• Application Number:
  US12/558,947
• Publication Number:
  US 20100070726A1
• Time in Patent Office: 1,982 Days
• Field of Search: 711/162
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/1466 to make the backup process non-disruptive
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

A system and method for using a snapshot as a data source is described. In some cases, the system stores a snapshot and an associated data structure or index to storage media to create a secondary copy of a volume of data. In some cases, the associated index includes application specific data about a file system or other application that created the data to identify the location of the data. The associated index may include three entries, and may be used to facilitate the recovery of data via the snapshot.

Claims

1. In a data management system residing within a private computer network that includes one or more data storage resources, a method of creating an index of data stored on a primary volume of a client computer coupled to the private computer network, the method comprising:

performing a snapshot of data stored on the primary volume of the client computer using a hardware-based snapshot mechanism,

wherein the performed snapshot includes a point in time representation of the data on the primary volume; and

,

wherein the snapshot creates pointers, without creating another physical copy of all the data, that map to specific disk blocks;

receiving the performed snapshot of the data stored on the primary volume at a media agent within the data management system,

wherein the media agent is configured to transfer the received snapshot to removable storage media;

transferring the received snapshot to one or more removable storage media associated with the media agent,

wherein the removable storage media includes a secondary copy of at least some of the data stored on the primary volume;

receiving information associated with the snapshot of data stored on the primary volume,

wherein the received information includes;

application context information, wherein the application context information identifies an application that created the data;

snapshot metadata, wherein the snapshot metadata identifies the hardware-based snapshot mechanism that performed the snapshot; and

storage media information, wherein the storage media information identifies the removable storage media that includes the secondary copy of the data stored on the primary volume; and

storing the received information in one or more indices that include entries for individual files imaged by the snapshot,

wherein the one or more indices are located within the media agent or within a data storage management control server configured to transmit information to storage resources coupled to the private computer network; and

,

wherein the one or more indices and snapshot permit granular recovery of individual files by permitting access to portions of the individual files without having to recover an entire individual file.

2. The method of claim 1, further comprising:

receiving a request to restore at least a portion of the data on the primary volume of the data;

identifying, via the storage media information, the removable storage media that includes the secondary copy of the data on the primary volume;

accessing the secondary copy of the data on the primary volume to retrieve the snapshot stored on the removable storage media;

identifying, via the snapshot metadata, the snapshot mechanism that performed the retrieved snapshot;

identifying, via the application context information, the application that created the at least portion of the data; and

retrieving the at least portion of the data using information from the retrieved snapshot, the snapshot mechanism, and the application that created the at least portion of the data.

3. The method of claim 1, further comprising:

receiving a request to restore at least a portion of the data on the primary volume of the data;

identifying via the storage media information, the snapshot metadata, and the application context information, a location of the at least portion of the data; and

retrieving the requested at least portion of the data.

4. The method of claim 1, wherein the application context information includes information associated with an original mount point of the snapshot of the data and a subsequent mount point of the snapshot of the data, wherein the original mount point and the subsequent mount point are different from each other and track information associated with movement of the data.

5. The method of claim 1, further comprising:

directly reading a portion of data from the snapshot to restore individual files identified from the application context information.

6. The method of claim 1, further comprising:

storing the index to the removable storage media, wherein the removable storage media includes at least one magnetic tape that is indexed by a data storage manager that controls the one or more data storage resources within the private computer network.

7. A system, at least partly implemented in hardware, for creating a secondary copy of a primary volume of data, wherein the system is part of a data storage enterprise, the system comprising:

a snapshot component, wherein the snapshot component is configured to create a snapshot of a primary volume of data at a specific point in time;

wherein the snapshot component creates pointers, without creating another physical copy of all the data, that map to specific disk blocks;

an index component, wherein the index component is configured to build an index associated with the snapshot component,

wherein the index includes context information related to a logical location of one or more data objects imaged by the snapshot,

wherein the context information includes information identifying the logical location of the primary volume of data within the data storage enterprise,

wherein the index component accesses or creates snapshot metadata and storage media information,

wherein the snapshot metadata includes information associated with the created snapshot, and

wherein the storage media information identifies a storage media that includes the secondary copy of the data stored on the primary volume; and

,

a data transfer component, wherein the data transfer component is configured to transfer the snapshot created by the snapshot component and the index built by the index component to the storage media;

wherein the transfer of the snapshot and the index creates a secondary copy of the primary volume of data,

wherein the secondary copy is capable of receiving queries for restoring individual files imaged by the snapshot; and

,

wherein the index permits recovery of portions of the individual files by permitting access to portions of individual files within the secondary copy.

8. The system of claim 7, wherein the index includes:

a first entry that contains information identifying archive files associated with the primary volume of data;

a second entry that contains information identifying data objects within the primary volume of data; and

a third entry that contains context information associated with a state of the primary volume of data at the specific point in time.

9. The system of claim 7, wherein the index includes:

information associating data objects imaged by the snapshot with information identifying a characteristic of an application that created the data objects.

10. The system of claim 7, wherein the index includes:

information associating the snapshot with resources used to create the snapshot, wherein the information includes information identifying one or more magnetic tapes that store the snapshot, information identifying offsets on the one or more magnetic tapes that store the snapshot, and information that identifies blocks in the snapshot for the secondary copy of the data object.

11. The system of claim 7, wherein the index includes:

information identifying two or more logical locations within the data storage enterprise where the snapshot imaged the primary volume of data.

12. The system of claim 7, wherein the data transfer component includes the snapshot component and the index component.

13. A non-volatile computer-readable medium containing executable code that causes a data storage system to perform a method of creating a backup copy of a data set, the method comprising:

generating a point in time copy of a data set;

storing the point in time copy of the data set to storage media;

wherein the point in time copy is created using pointers, without creating another physical copy of all the data, that map to specific disk blocks;

building a data structure associated with the point in time copy of the data set,

wherein the data structure includes;

information identifying data objects within the point in time copy of the data set;

information identifying secondary copies associated with the data objects; and

storing the data structure to the storage media,

wherein the data structure permits granular recovery of data objects by permitting access to portions of individual data objects within secondary copies.

14. The computer-readable medium of claim 13, wherein information identifying system resources includes information indicating a location of system resources of the data storage system when the instant image of the data set was generated.

15. The computer-readable medium of claim 13, wherein generating the instant image of the data set includes:

performing continuous data replication on the data set;

identifying one or more recovery points during the performed continuous data replication; and

,

associating the one or more recovery points as the instant image of the data set.

16. The computer-readable medium of claim 13, wherein storing the instant image of the data set includes:

identifying a proper subset of data blocks associated with the instant image of the data set that satisfy a criteria; and

,

storing a portion of the instant image of the data set associated with the proper subset of blocks to the storage media.

17. The computer-readable medium of claim 13,

wherein the data structure further includes:

information identifying system resources used to create the data objects;

information identifying an application that created the data;

information identifying a hardware-based snapshot mechanism that performed the snapshot; and

,

information identifying a removable storage media that includes the secondary copy of the data stored on the primary volume.