Method and system for virtual on-demand recovery for real-time, continuous data protection

• US 7,788,521 B1
• Filed: 07/20/2005
• Issued: 08/31/2010
• Est. Priority Date: 07/20/2005
• Status: Active Grant

• Current Assignee: Quest Software, Inc.
• Original Assignee: BakBone Software, Inc. (Quest Software, Inc.)
• Inventors: Sim-Tang, Siew Yong
• Primary Examiner(s): Baderman; Scott T
• Assistant Examiner(s): PATEL, KAMINI B
• Application Number:
  US11/185,313
• Time in Patent Office: 1,868 Days
• Field of Search: 714/4, 714/20
• US Class Current: 714/4.12
• 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 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

A data management system or “DMS” provides an automated, continuous, real-time, substantially no downtime data protection service to one or more data sources associated with a set of application host servers. To facilitate the data protection service, a host driver embedded in an application server captures real-time data transactions, preferably in the form of an event journal that is provided to other DMS components. The driver functions to translate traditional file/database/block I/O and the like into a continuous, application-aware, output data stream. The host driver includes an event processor. When an authorized user determines that a primary copy of the data in the host server has become incorrect or corrupted, the event processor can perform a recovery operation to an entire data source or a subset of the data source using former point-in-time data in the DMS. The recovery operation may have two phases. First, the structure of the host data in primary storage is recovered to the intended recovering point-in-time. Thereafter, the actual data itself is recovered. The event processor enables such data recovery in an on-demand manner, in that it allows recovery to happen simultaneously while an application accesses and updates the recovering data.

Claims

1. A method comprising:

storing data associated with a data source into a data store remote from the data source;

streaming to the data store, as an associated data history of the data source, an application-aware real-time event data stream comprising event-identifying data, metadata, and data changes;

responsive to a determination that given data in the data source is to be recovered to a former point-in-time state;

retrieving from the data store a structure of the given data;

presenting the structure of the given data to an application associated with the data source so that, from a point-of-view of the application, the data source is recovered; and

synchronizing the data source to the structure of the given data;

wherein the data source remains accessible to the application during the retrieving, presenting, and synchronizing step; and

as the data source is synchronized and following the synchronization, generating and forwarding to the data store the application-aware real-time event data stream.

2. The method of claim 1, wherein streaming step is performed by a host driver coupled with the data source and connected to the data store.

3. The method of claim 2, wherein the host driver comprises:

an I/O filter to intercept data events between the application and its primary data storage;

a data agent that manages a data source in the data source;

a control agent that receives commands from the data store; and

an event queue associated with the data agent.

4. The method of claim 3, wherein the data agent comprises at least one of:

an application module to receive application-level events;

a database module to receive database-level events;

an I/O module which instructs the I/O filter to capture a set of one or more I/O events of interest to the data agent and forwards events received from the I/O filter to the event queue for processing; and

an event processor which instructs the application module to capture different application-level events and instructs the database module to capture different database-level events.

5. The method of claim 4, wherein the event processor implements a finite state machine.

6. The method of claim 4, wherein the state of the event processor is dependent upon at least one event described in an event processor data protection incident table.

7. The method of claim 4, wherein the event processor generates and outputs the application-aware real-time event data stream.

8. The method of claim 1, wherein a most current data state in the data store must match an associated data state of the data source at all times.

9. The method of claim 1, wherein the retrieving step results in, from information in the data store, a sorted data list used to generate the structure in the data source.

10. The method of claim 9, comprising filtering access requests during the step of retrieving the structure of the given data.

11. The method of claim 10, comprising failing WRITE requests.

12. The method of claim 10, comprising filtering READ requests synchronously.

13. The method of claim 12, comprising serving a READ request from the data source.

14. The method of claim 12, comprising failing a READ request.

15. The method of claim 9, comprising filtering access requests while the given data is synchronized to the former point-in-time state.

16. The method of claim 15, comprising the steps of:

determining, via the sorted data list, whether an access request is for data that has not been retrieved; and

if the access request is for data that has not been retrieved, retrieving the data requested.

17. The method of claim 16, comprising marking, in the sorted data list, a given data item as retrieved if the application-aware real-time event data stream stored by the data store includes information associated with the given data item.

18. The method of claim 1, comprising the step of re-initiating protection of a given data source following the synchronizing step.

19. A method comprising:

storing data associated with a data source into a data store remote from the data source;

streaming to the data store, as an associated data history of the data source, an application-aware real-time event data stream comprising event-identifying data, metadata, and data changes;

responsive to a determination that given data in the data source is to be recovered to a former point-in-time state;

adjusting a current state of the data source at the data store by moving a past state of the data source to the current state of the data source;

retrieving the current state of the data source from the data store;

presenting the current state of the data source to an application associated with the data source so that from a point-of-view of the application, the data source is recovered; and

synchronizing the data source using the current state of the data source retrieved from the data store;

wherein the data source remains accessible to the application during the adjusting, retrieving, presenting, and synchronizing step; and

as the data source is synchronized and following the synchronization, generating and forwarding to the data store the application-aware real-time event data stream.

20. An apparatus comprising:

a processor;

software code executed by the processor to implement a host driver;

wherein the host driver is coupled with a data source and further connected to a data store in a remote location;

software code executed by the processor to continuously generate and forward to the data store, as an associated point-in-time data history of the data source, an application-aware real-time event data stream comprising event-identifying data, metadata, and data changes;

software code executed by the processor and responsive to a determination that given data in the data source is to be recovered to a former point-in-time state;

adjusts a current state of the data source at the data store by moving a past state of the data source to the current state of the data source;

retrieves the current state of the data source from the data store;

presents the current state of the data source to an application associated with the data source so that from a point-of-view of the application, the data source is recovered; and

synchronizes the data source using the current state of the data source retrieved from the data store;

software code executed by the processor ensures that the data source remains accessible to the application during the adjusts, retrieves, presents, and synchronizes step; and

as the data source is synchronized and following the synchronization, software code executed by the processor generates and forwards to the data store the application-aware real-time event data stream.

21. The apparatus of claim 20, comprising software code executed by the processor to recover a structure of the data source.

22. The apparatus of claim 20, comprising an interface to initiate the data recovery operation.