Tracking write operations for incremental backups of data

• US 9,195,670 B1
• Filed: 03/13/2013
• Issued: 11/24/2015
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Mam, Neelabh
• Primary Examiner(s): Perveen, Rehana
• Assistant Examiner(s): Tran, Loc
• Application Number:
  US13/799,725
• Time in Patent Office: 986 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• 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

Approaches are described for tracking write operations in an operating system environment which can be used to perform incremental backups of data. In particular, the approaches described herein enable a driver to begin tracking write operations being performed on a volume device (or snapshot of a volume) without having to reboot the system and without causing interruption to operations being performed on the volume. The tracking is enabled by applying a patch to a driver provided by the operating system to replace an original write handler of the driver with an alternate write handler. This alternate handler is used to track the sequence of write operations performed on a snapshot of the volume device. An active bitmap is maintained for recording changed blocks resulting from the write operations. Tins active bitmap can subsequently be used to perform an incremental backup of the volume device based on the snapshot.

Claims

1. A computer implemented method for tracking write operations to perform incremental backups, the method comprising:

accessing a driver of an operating system on a computer, the driver creating a snapshot volume of a physical volume of the computer;

applying a patch to the driver, the patch configured to replace an original write handler of the driver with a first alternate write handler, the first alternate write handler tracking a sequence of write operations performed on the snapshot volume, the tracking of the sequence of write operations performed on the snapshot volume being caused by invoking the first alternate write handler, and the tracking of the sequence of write operations performed on the snapshot volume maintaining a first active bitmap recording the sequence of write operations performed on the snapshot volume over a time interval;

accessing a second alternate write handler when an input-output manager of the operating system writes to the physical volume, the second alternate write handler tracking a sequence of write operations performed on the physical volume, the tracking of the sequence of write operations performed on the physical volume being caused by invoking the second alternate write handler, and the tracking of the sequence of write operations performed on the physical volume maintaining a second active bitmap recording the sequence of write operations performed on the physical volume over the time interval;

determining one or more files to be excluded from the incremental backup;

executing a delete operation on the snapshot volume to remove the one or more files from the snapshot, wherein the delete operation is handled by the first alternate write handler;

merging the first active bitmap with the second active bitmap to produce a master bitmap, so that the delete operation is reflected in the master bitmap; and

performing an incremental backup of the physical volume based on the snapshot volume and based on the master bitmap to maintain consistent backup during continued execution of the operating system and without disruption to the write operations on the physical volume, wherein the one or more files are excluded from the incremental backup when the incremental backup is preformed based on the snapshot volume and based on the master bitmap.

2. The computer implemented method of claim 1, wherein accessing the driver of the operating system further comprises:

invoking an application programming interface (API) exposed by the operating system to directly reference a driver of the volume shadow copy service (VSS) provided by the operating system.

3. The computer implemented method of claim 1, which further includes computing a logical AND of the first active bitmap with the second active bitmap in order to merge the first active bitmap with the second active bitmap to produce the master bitmap.

4. A computing system, comprising:

at least one processor; and

memory including instructions that, when executed by the at least one processor, cause the computing system to;

access a driver of an operating system on a computer, the driver creating a snapshot volume of a physical volume of the computer;

apply a patch to the driver, the patch configured to replace an original write handler of the driver with a first alternate write handler, the first alternate write handler tracking a sequence of write operations performed on the snapshot volume, the tracking of the sequence of write operations performed on the snapshot volume being caused by invoking the first alternate write handler, and the tracking of the sequence of write operations performed on the snapshot volume maintaining a first active bitmap recording the sequence of write operations performed on the snapshot volume over a time interval;

access a second alternate write handler when an input-output manager of the operating system writes to the physical volume, the second alternate write handler tracking a sequence of write operations performed on the physical volume, the tracking of the sequence of write operations performed on the physical volume being caused by invoking the second alternate write handler, and the tracking of the sequence of write operations performed on the physical volume maintaining a second active bitmap recording the sequence of write operations performed on the physical volume over the time interval;

determine one or more files to be excluded from the incremental backup;

execute a delete operation on the snapshot volume to remove the one or more files from the snapshot, wherein the delete operation is handled by the first alternate write handler;

merge the first active bitmap with the second active bitmap to produce a master bitmap, so that the delete operation is reflected in the master bitmap; and

perform an incremental backup of the physical volume based on the snapshot volume and based on the master bitmap to maintain consistent backup during continued execution of the operating system and without disruption to the write operations on the physical volume, wherein the one or more files are excluded from the incremental backup when the incremental backup is preformed based on the snapshot volume and based on the master bitmap.

5. The computing system of claim 4, wherein the memory further includes instructions executed by the at least one processor to cause the computing system to:

invoke an application programming interface (API) exposed by the operating system to directly reference a driver of the volume shadow copy service (VSS) provided by the operating system.

6. The computing system of claim 4, wherein the memory further includes instructions executed by the at least one processor to cause the computing system to compute a logical AND of the first active bitmap with the second active bitmap in order to merge the first active bitmap with the second active bitmap to produce the master bitmap.

7. A non-transitory computer readable storage medium storing one or more sequences of instructions that, when executed by one or more processors, cause the one or more processors to:

access a driver of an operating system on a computer, the driver creating a snapshot volume of a physical volume of the computer;

apply a patch to the driver, the patch configured to replace an original write handler of the driver with a first alternate write handler, the first alternate write handler tracking a sequence of write operations performed on the snapshot volume, the tracking of the sequence of write operations performed on the snapshot volume being caused by invoking the first alternate write handler, and the tracking of the sequence of write operations performed on the snapshot volume maintaining a first active bitmap recording the sequence of write operations performed on the snapshot volume over a time interval;

access a second alternate write handler when an input-output manager of the operating system writes to the physical volume, the second alternate write handler tracking a sequence of write operations performed on the physical volume, the tracking of the sequence of write operations performed on the physical volume being caused by invoking the second alternate write handler, and the tracking of the sequence of write operations performed on the physical volume maintaining a second active bitmap recording the sequence of write operations performed on the physical volume over the time interval;

determine one or more files to be excluded from the incremental backup;

execute a delete operation on the snapshot volume to remove the one or more files from the snapshot, wherein the delete operation is handled by the first alternate write handler;

merge the first active bitmap with the second active bitmap to produce a master bitmap, so that the delete operation is reflected in the master bitmap; and

perform an incremental backup of the physical volume based on the snapshot volume and based on the master bitmap to maintain consistent backup during continued execution of the operating system and without disruption to the write operations on the physical volume, wherein the one or more files are excluded from the incremental backup when the incremental backup is preformed based on the snapshot volume and based on the master bitmap.

8. The non-transitory computer readable storage medium of claim 7, further comprising instructions that, when executed by the one or more processors, cause the one or more processors to access the driver of the operating system by invoking an application programming interface (API) exposed by the operating system to directly reference a driver of the volume shadow copy service (VSS) provided by the operating system.

9. The non-transitory computer readable storage medium of claim 7, further comprising instructions that, when executed by the one or more processors, cause the one or more processors to compute a logical AND of the first active bitmap with the second active bitmap in order to merge the first active bitmap with the second active bitmap to produce the master bitmap.