SYSTEMS AND METHODS FOR PERFORMING DISCRETE DATA REPLICATION

• US 20100179941A1
• Filed: 12/09/2009
• Published: 07/15/2010
• Est. Priority Date: 12/10/2008
• Status: Active Grant

• Current Assignee: CommVault Systems Incorporated
• Original Assignee: CommVault Systems Incorporated
• Inventors: Prahlad, Anand, Agrawal, Vijay H.
• Granted Patent: US 9,495,382 B2
• Time in Patent Office: Days
• US Class Current: 707/624
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 16/1815 Journaling file systems
• CPC Class Codes: G06F 16/184 implemented as replicated file system
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

Systems and methods for performing intelligent replication of production data on a source storage device. In certain examples, a full backup of the production data is first performed and stored on a destination system. A journal module on the storage device (e.g., a shared storage device), or on at least one source system, tracks files on the storage device that change during a particular period of time. Following this period, a snapshot is taken of the production data. Upon mounting the snapshot, the replication system uses the journal information to identify modified files, conduct a block-level comparison of only the modified files with corresponding files on the destination system, and identify the particular data blocks that changed. The replication system then replicates only the changed blocks to the destination system. Certain systems further store information indicating a source system time of a known good state of the production data.

Claims

1. A method for replicating data in a computer network, the method comprising:

performing at a first time a full backup of source data on a source storage device, the source data comprising a plurality of source files, to copy replication data to a destination storage device, the replication data comprising a plurality of destination files corresponding to the plurality of source files;

following the full backup, identifying changed source files by tracking at a logical level which of the plurality of source files changes between the first time and a second time;

performing a snapshot of the source data to capture a point-in-time copy of the source data at the second time;

mounting the snapshot to provide access to the point-in-time copy of the source data;

comparing blocks of the changed source files within the point-in-time copy of the source data with blocks of the corresponding destination files to detect changed blocks between the changed source files and the corresponding destination files; and

replicating only the changed blocks of the changes source files to the replication data on the destination storage device.

2. The method of claim 1, additionally comprising, prior to performing the snapshot, quiescing one or more applications having access to the source data on the source storage device.

3. The method of claim 2, wherein said quiescing is performed at a known good state of the one or more applications.

4. The method of claim 2, additionally comprising instructing the one or more applications to assume a known good state.

5. The method of claim 1, wherein the source storage device comprises a shared storage device.

6. The method of claim 5, wherein said tracking comprises maintaining a journal file on the shared storage device with entries indentifying the changed source files.

7. The method of claim 1, additionally comprising transmitting with the changed blocks time information indicative of the second time, wherein the time information is relative to a clock associated with the source storage device.

8. The method of claim 7, additionally comprising, following said replicating only the changed blocks:

performing a storage operation on the replication data to generate copied data; and

logically associating the copied data with the time information indicative of the second time

9. The method of claim 1, wherein the duration between the first time and the second time is based on a storage policy stored in a preference database.

10. A system for performing data replication in a computer network environment, the system comprising:

a shared storage device configured to store source data as a plurality of source files;

a first source computing device having a first application operative to write data to the plurality of source files stored on the shared storage device;

a second source computing device having a second application operative to write data to the plurality of source files stored on the shared storage device;

a journal module configured to identify changed source files by tracking logical changes to the plurality of source files on the shared storage device between a first time and a second time; and

a data agent module configured to,

instruct a creation of a snapshot of the source data to capture a state of the source data at the second time,

instruct a mounting of the snapshot,

access the mounted snapshot to compare blocks of the changed source files with blocks of corresponding replication files on a replication storage device to detect inconsistent blocks between the changed source files and the corresponding replication files, and

transmit the detected inconsistent blocks of the changes source files to the replication storage device without transmitting other blocks of the source data.

11. The system of claim 10, wherein the journal module resides on the shared storage device.

12. The system of claim 11, wherein the journal module comprises a new technology file system (NTFS) change journal.

13. The system of claim 10, wherein the data agent module is configured to compare the blocks using a secure hash algorithm.

14. The system of claim 10, wherein the source data consists essentially of application-specific data.

15. The system of claim 10, further comprising a replication module in communication with the replication storage device, the replication module being in network communication with the data agent and operative to write the detected inconsistent blocks to the replication files.

16. The system of claim 15, wherein the replication module is further configured to direct a storage operation to be performed on at least a portion of the replication files to generate copied data.

17. The system of claim 16, wherein the replication module is further configured to logically associate the copied data with a time stamp indicative of the second time.

18. The system of claim 17, wherein the second time identifies a time at which the source data is in a known good state.

19. A replication system comprising:

means for storing source data accessible to both a first source computing device and a second source computing device, the source data being stored as a plurality of source files;

means for performing a full backup of the source data at a first time, the full backup resulting in replication data being stored on a destination storage device, the replication data comprising a plurality of destination files corresponding to the plurality of source files;

means for tracking logical changes to the plurality of source files between the first time and a second time to identify changed source files;

means for mounting a snapshot capturing a state of the source data at the second time;

means for comparing blocks of the changed source files with blocks of the corresponding destination files to detect changed blocks; and

means for replicating only the changed blocks to the destination storage device.

20. The replication system of claim 19, additionally comprising means for performing a storage operation on the replication data to generate copied data and for logically associating the copied data with time information indicative of the second time.