Continuous data protection using a write filter

Patent metadata

Field	Value
Publication number	US-2020356442-A1
Application number	US-201916549719-A
Country	US
Kind code	A1
Filing date	Aug 23, 2019
Priority date	May 10, 2019
Publication date	Nov 12, 2020
Grant date	—

Abstract

A reference snapshot of a storage is stored. Data changes that modify the storage are received. The data changes are captured by a write filter of the storage. The received data changes are logged. The data changes occurring after an instance time of the reference snapshot are applied to the reference snapshot to generate a first incremental snapshot corresponding to a first intermediate reference restoration point. The data changes occurring after an instance time of the first incremental snapshot are applied to the first incremental snapshot to generate a second incremental snapshot corresponding to a second intermediate reference restoration point.

First claim

What is claimed is:

1 . A method, comprising:
storing a reference snapshot of a storage; receiving data changes that modify the storage, wherein the data changes are captured by a write filter of the storage; logging the received data changes; applying to the reference snapshot data changes occurring after an instance time of the reference snapshot to generate a first incremental snapshot corresponding to a first intermediate reference restoration point; and applying to the first incremental snapshot data changes occurring after an instance time of the first incremental snapshot to generate a second incremental snapshot corresponding to a second intermediate reference restoration point.

2 . The method of claim 1 , wherein the write filter is configured to receive a notification of a snapshot of a workload being created.

3 . The method of claim 2 , wherein in response to receiving the notification of the snapshot of the workload being created, the write filter is configured to insert a snapshot marker into a stream of IOs.

4 . The method of claim 3 , further comprising:
determining that a log entry includes the snapshot marker; and generating the first intermediate reference restoration point.

5 . The method of claim 4 , wherein generating the first intermediate reference restoration point comprises:
cloning a tree data structure corresponding to the reference snapshot; and applying the logged data changes to the cloned tree data structure.

6 . The method of claim 1 , further comprising determining that a gap exists in a log of the received data changes.

7 . The method of claim 6 , further comprising requesting a second reference snapshot of the storage.

8 . The method of claim 7 , further comprising generating a full reference restoration point based on the second reference snapshot.

9 . The method of claim 1 , wherein the received data changes include corresponding sequence numbers.

10 . The method of claim 9 , wherein the corresponding sequence numbers include corresponding incarnation identifiers and corresponding change identifiers.

11 . The method of claim 1 , wherein the write filter is attached to a workload of the storage prior to the reference snapshot being initiated.

12 . The method of claim 1 , further comprising receiving a request to restore the storage to a particular moment in time.

13 . The method of claim 12 , further comprising determining a reference restoration point associated with the particular moment in time.

14 . The method of claim 13 , further comprising:
determining that the determined reference restoration point is equal to the particular moment in time; and providing data associated with the reference restoration point.

15 . The method of claim 13 , further comprising:
determining that the determined reference restoration point is not equal to the particular moment in time; cloning a tree data structure associated with the determined reference restoration point; and modifying the cloned tree data structure by applying one or more data changes included in a log to the cloned tree data structure.

16 . The method of claim 15 , further comprising providing data associated with the modified cloned tree data structure.

17 . A computer program product, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:
storing a reference snapshot of a storage; receiving data changes that modify the storage, wherein the data changes are captured by a write filter of the storage; logging the received data changes; applying to the reference snapshot data changes occurring after an instance time of the reference snapshot to generate a first incremental snapshot corresponding to a first intermediate reference restoration point; and applying to the first incremental snapshot data changes occurring after an instance time of the first incremental snapshot to generate a second incremental snapshot corresponding to a second intermediate reference restoration point.

18 . The computer program product of claim 17 , wherein the received data changes include corresponding sequence numbers.

19 . The computer program product of claim 18 , wherein the corresponding sequence numbers include corresponding incarnation identifiers and corresponding change identifiers.

20 . A system, comprising:
a processor configured to:
store a reference snapshot of a storage;
receive data changes that modify the storage, wherein the data changes are captured by a write filter of the storage;
log the received data changes;
apply to the reference snapshot data changes occurring after an instance time of the reference snapshot to generate a first incremental snapshot corresponding to a first intermediate reference restoration point; and
apply to the first incremental snapshot data changes occurring after an instance time of the first incremental snapshot to generate a second incremental snapshot corresponding to a second intermediate reference restoration point; and
a memory coupled to the processor and configured to provide the processor with instructions.

Assignees

• Cohesity Inc

Inventors

• Agarwal Shobhit
• Manjunath Chinmaya
• Nerella Kishan Venkata Sravan
• Patwardhan Ashish

Classifications

• G06F11/1471

  involving logging of persistent data for recovery · CPC title

• G06F11/1461

  Backup scheduling policy · CPC title

• G06F11/1469

  Backup restoration techniques · CPC title

• G06F11/1451 Primary

  by selection of backup contents · CPC title

• G06F11/1435

  using file system or storage system metadata · CPC title