EFFICIENT VOLUME-LEVEL REPLICATION OF DATA VIA SNAPSHOTS IN AN INFORMATION MANAGEMENT SYSTEM

• US 20160034481A1
• Filed: 07/29/2014
• Published: 02/04/2016
• Est. Priority Date: 07/29/2014
• Status: Active Grant

• Current Assignee: CommVault Systems Incorporated
• Original Assignee: CommVault Systems Incorporated
• Inventors: KUMARASAMY, Paramasivam, CHEDALAVADA, Durga Prasad
• Granted Patent: US 10,031,917 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/16 Error detection or correction of the data by redundancy in hardware
• 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

Abstract

The illustrative systems and methods use a special-purpose volume-replicating server(s) to offload client computing devices operating in a production environment. The production environment may remain relatively undisturbed while production data is replicated to a geographically distinct destination. Replication is based in part on hardware-based snapshots generated by a storage array that houses production data. The illustrative volume-replicating server efficiently moves data from snapshots on a source storage array to a destination storage array by transferring only changed blocks for each successive snapshot, i.e., transferring incremental block-level changes. Periodic restore jobs may be executed by destination clients to keep current with their corresponding source production clients. Accordingly, after the source data center goes offline, production data may be speedily restored at the destination data center after experiencing only minimal downtime of production resources. By employing block-level techniques, the disclosed solutions avoid the file-based data management approaches of the prior art, which tend to be too time-consuming and resource-intensive for the present scenario.

Claims

1. A method comprising:

in an information management system managed by a storage manager, replicating a source volume in a first storage array to a destination volume in a second storage array, wherein the source volume comprises data generated by a first client computing device in communication with a first logical unit number on the first storage array that comprises the source volume,

wherein the replicating comprises;

generating and storing, by the first storage array, a first snapshot of the first logical unit number comprising the source volume,

generating and storing, by the first storage array, after the first snapshot, a second snapshot of the first logical unit number comprising the source volume,

transferring, by a volume-replicating server, to the destination volume in the second storage array, based on a mapping of changed blocks received by the volume-replicating server from the first client computing device, only the changed blocks of the second snapshot relative to the first snapshot, and

substituting, by the volume-replicating server, the changed blocks in the destination volume for any corresponding pre-existing blocks therein, thereby replicating, at a block level, the second snapshot to the destination volume; and

restoring the second snapshot, at a block-level, from the destination volume to a second client computing device in communication with a second logical unit number on the second storage array, wherein the second logical unit number comprises the destination volume.

2. The method of claim 1 further comprising:

executing an application on the second client computing device, wherein the application uses the destination volume for primary data.

3. The method of claim 1 wherein the volume-replicating server offloads the first client computing device by transferring the changed blocks to the second volume on the second storage array.

4. The method of claim 1 wherein the volume-replicating server offloads the first client computing device by (i) extracting the changed blocks from the second snapshot on the first storage array, based on the mapping received from the first client computing device, and also (ii) transferring the extracted changed blocks to the second volume on the second storage array.

5. The method of claim 1 wherein the generating and storing of the snapshots by the first storage array is performed in response to instructions received from the storage manager.

6. The method of claim 1 wherein the generating and storing of the snapshots by the first storage array is performed in response to instructions received from a data agent executing on the first client computing device.

7. The method of claim 1 wherein the generating and storing of the snapshots by the first storage array is performed in response to instructions received from the volume-replicating server.

8. The method of claim 1 wherein the storage manager coordinates the timing of the generating of the snapshots by the first storage array with the corresponding mapping of the changed blocks performed by the first client computing device.

9. The method of claim 1 wherein a data agent that executes on the first client computing device performs the mapping of the changed blocks relative to an immediately preceding snapshot.

10. The method of claim 1 wherein the substituting of the changed blocks is performed by the volume-replicating server.

11. The method of claim 1 wherein the block-level restoring of the second snapshot is initiated at the second client computing device, at least in part by mounting to the second client computing device, the second logical unit number that comprises the destination volume.

12. An information management system comprising:

a volume-replicating server in communication with a first storage array and a second storage array;

a first client computing device in communication with the client-replicating server and with the first storage array;

the first storage array, comprising a source volume comprising primary data generated by the first client computing device, wherein the source volume is configured as a first logical unit number mounted to the first client computing device;

wherein the first storage array is configured to;

generate and store a first snapshot of the first logical unit number comprising the source volume, and

generate and store, after the first snapshot, a second snapshot of the first logical unit number comprising the source volume;

wherein the volume-replicating server is configured to;

extract one or more changed blocks from the second snapshot on the first storage array, based on a mapping, received from the first client computing device, of changed blocks relative to the first snapshot,

transfer the extracted changed blocks to a destination volume in the second storage array, and

substitute the changed blocks in the destination volume for any corresponding pre-existing blocks therein, wherein the destination volume in the second storage array is a volume-level replica of the second snapshot.

13. The system of claim 12 further comprising:

a second client computing device comprising an application, wherein the application is configured to execute on the second client computing device based on the destination volume, and wherein the second snapshot in the destination volume is restored as primary data for the application.

14. The system of claim 12 wherein the volume-replicating server is further configured to:

instruct the first client computing device to generate the map of changed blocks in the second snapshot relative to the first snapshot, based on tracking, by a data agent executing on the first client computing device, which blocks are changed in the first volume by write operations performed by the first client computing device; and

instruct the first client computing device to transmit the map of changed blocks to the volume-replicating server.

15. The system of claim 12 further comprising a storage manager that is configured to:

instruct the first client computing device to generate the map of changed blocks in the second snapshot relative to the first snapshot, based on tracking, by a data agent executing on the first client computing device, which blocks are changed in the first volume by write operations performed by the first client computing device; and

instruct the first client computing device to transmit the map of changed blocks to the volume-replicating server.

16. A method for volume-level replication of data generated in an information management system, the method comprising:

generating and storing, by a first storage array in the information management system, a first snapshot of a first logical unit number comprising a source volume on the first storage array, wherein the source volume comprises data generated by a first client computing device in the information management system;

generating and storing, after the first snapshot, a second snapshot of the first logical unit number comprising the source volume;

extracting, by a volume-replicating server in the information management system, one or more changed blocks from the second snapshot on the first storage array, based on a mapping of changed blocks relative to the first snapshot, wherein the mapping is received from the first client computing device;

transferring, by the volume-replicating server, the extracted changed blocks to a destination volume in a second storage array; and

substituting the changed blocks in the destination volume for any corresponding pre-existing blocks therein, wherein the destination volume in the second storage array is a volume-level replica of the second snapshot.

17. The method of claim 16 further comprising:

restoring the second snapshot, at a block-level, from the destination volume to a second client computing device in communication with a second logical unit number on the second storage array, wherein the second logical unit number comprises the destination volume.

18. The method of claim 16 further comprising:

restoring the second snapshot, at a block-level, from the destination volume to a second client computing device in communication with a second logical unit number on the second storage array, wherein the second logical unit number comprises the destination volume; and

executing an application on the second client computing device, wherein the application uses the destination volume for primary data.

19. The method of claim 16 wherein the generating and storing of the snapshots by the first storage array is performed in response to instructions received from the volume-replicating server.