CREATING FREQUENT APPLICATION-CONSISTENT BACKUPS EFFICIENTLY

• US 20070276885A1
• Filed: 08/02/2006
• Published: 11/29/2007
• Est. Priority Date: 05/29/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Anand, Karandeep Singh, Fries, Robert M., Singla, Amit, Valiyaparambil, Manoj K., Ali, Abid, Badami, Vinay S., Sahasranaman, Vivek
• Granted Patent: US 7,613,750 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

Data can be protected at a production server in a virtually continuous fashion, without necessarily imposing severe constraints on the source application(s). For example, a production server can create an application-consistent backup of one or more volumes, the backups corresponding to a first instance in time. A volume filter driver can monitor data changes in each volume using an in-memory bitmap, while a log file and/or update sequence number journal can keep track of which files have been added to or updated. The volume updates are also consistent for an instance (later) in time. At the next replication cycle, such as every few minutes (however configured), the volume filter driver passes each in-memory bitmap to the physical disk on the production server. The production server then sends the updates to the backup server, which thus stores application-consistent backups for the volume for multiple instances of time.

Claims

1. At a production server in a computerized environment in which one or more production servers backup data to be protected on one or more volumes at one or more backup servers, a method of replicating production server data in a virtually continuous, consistent fashion, such that recent data can be easily recovered from the backup server, comprising the acts of:

sending a copy of data for one or more volumes from a production server to a backup server, wherein the data are consistent for a first instance of time;

identifying one or more changes to the data for the one or more volumes in one or more volume log files;

upon identifying a replication cycle event, saving the one or more data changes in the one or more volume log files, wherein the one or more data changes are consistent for a second instance of time; and

sending to the backup server a copy of the one or more data changes for the one or more volumes, such that the backup server has a copy of data for the one or more volumes that are valid for a first instance of time and a second instance of time.

2. The method as recited in claim 1, further comprising saving file-level data changes for the volume in one of a change filter, a change journal, or a USN journal.

3. The method as recited in claim 2, further comprising an act of correlating the one or more volume log files with one of the change filter, change journal, or USN journal to identify one or more changed files that correspond to the one or more data changes in each changed file.

4. The method as recited in claim 1, further comprising an act of marking the one or more data changes on any one of a byte level or a byte block level in the one or more volume log files.

5. The method as recited in claim 1, further comprising an act of identifying the changes to the data for the one or more volumes via one or more in-memory bitmaps, wherein the one or more in-memory bitmaps correspond to the second instance in time.

6. The method as recited in claim 5, further comprising an act of saving the one or more in-memory bitmaps to the one or more volume log files during the replication cycle event, wherein the one or more volume log files are stored on disk.

7. The method as recited in claim 5, further comprising the acts of:

freezing the one or more in-memory bitmaps corresponding to the second instance in time; and

creating a new set of one or more in-memory bitmaps corresponding to new writes to the one or more changed files for the third instance in time.

8. The method as recited in claim 1, wherein a volume filter driver receives the one or more data changes and applies the one or more data changes to the one or more volume log files.

9. The method as recited in claim 1, wherein the one or more data changes that are consistent for the first and second instances of time are at least one of application-consistent or file system-consistent.

10. The method as recited in claim 1, further comprising an act of changing a file path of a file corresponding to any of the one or more data changes at the production server, such that the file path at the production server is different from a path to the file at the backup server.

11. The method as recited in claim 10, further comprising a step for correlating the paths for the file at the production server and at the backup server, such that new changes to the files can be sent to the backup server with a change in the path for the file.

12. The method as recited in claim 11, wherein the step for correlating the file paths for the file comprises the acts of:

identifying an initial path for the file; and

storing the initial file path for the file at the production server.

13. The method as recited in claim 11, wherein the step for correlating the file paths for the file comprises the acts of:

scanning a USN journal at least a first time to cache the change in file path at the production server;

scanning the USN journal at least a second time to identify the initial file path at the production server; and

computing an adjusted path to the file at the backup server based on the first and second scans.

14. The method as recited in claim 1, further comprising act of sending a new update of volume data at the production server to the backup server, wherein the new update is consistent for a third instance of time, and wherein the time elapsed between the second and third instances of time is configurable for any one of less than about an hour, or less than about one half hour.

15. The method as recited in claim 14, further comprising an act of sending a request to the backup server for a copy of one or more files, wherein the request to the backup server for a copy of one or more files, wherein the request includes an indication that the one or more files are valid for one of the second or third instances in time.

16. The method as recited in claim 15, further comprising an act of receiving a recovery response from the backup server, wherein the recovery response includes a full copy of data for the requested one or more files as of the second or third instance of time.

17. At a backup server in a computerized environment in which one or more backup servers backup data from one or more volumes of one or more production servers, a method of replicating data of the one or more production server volumes in a virtually continuous, consistent fashion, such that recent data can be easily recovered from the backup server, comprising the acts of:

receiving one or more volume backups from a production server, wherein the one or more volume backups are consistent for an initial instance of time;

receiving one or more consistent backup updates, at least one of which is an application-consistent update to at least one of the one or more volume backups for a subsequent instance of time;

receiving a recovery request for data that are valid in accordance with the subsequent instance of time;

identifying the requested data for the subsequent instance of time at one or more backup server volumes, wherein the requested data include at least a portion of the at least one consistent backup update; and

sending the requested data that is valid for the subsequent instance of time to the production server.

18. The method as recited in claim 17, further comprising the acts of:

identifying a baseline full copy of the requested data;

identifying each of one or more consistent backup updates to the requested data that were received between receipt of the baseline full copy and receipt of the at least one backup update for the subsequent instance of time; and

combining the baseline full copy of the requested data with the identified one or more consistent backup updates to the requested data.

19. The method as recited in claim 18, wherein the wherein the one or more volume backups and the one or more consistent backup updates are at least one of application-consistent or file system-consistent.

20. At a production server in a computerized environment in which one or more production servers backup data to be protected at one or more backup servers, a computer program product having computer-executable instructions stored thereon that, when executed, cause one or more processors at the production server to perform a method of replicating production server data in a virtually continuous, application-consistent fashion, such that recent data can be easily recovered from the backup server, comprising the acts of:

sending a copy of data for one or more volumes from a production server to a backup server, wherein the data are consistent for a first instance of time;

identifying one or more changes to the data for the one or more volumes in one or more volume log files;

upon identifying a replication cycle event, saving the one or more data changes in the one or more volume log files, wherein the one or more data changes are consistent for a second instance of time; and

sending to the backup server a copy of the one or more data changes for the one or more volumes, such that the backup server has a copy of data for the one or more volumes that are valid for a first instance of time and a second instance of time.