Continuous Data Protection Using Allocate-on-Write Snapshots

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Traditional backup methods only restore data to the point in time of the last backup, which may be outdated and potentially compromised, requiring users to revert to older versions, and do not provide continuous protection against catastrophic failures.

Innovation Solution

A method and system for continuous data protection that divides a virtual volume into chunks, creates Point-in-Time (PiT) instances with a Temporary Virtual Volume (PTVV) for storing modifications, a re-allocation table for read access to the most recent versions, and a Continuous Data Protection (CDP) log for historic versions, prohibiting direct write access and allowing granular restore capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional backup methods are used, then data can be restored to the point in time of the last backup, but the restored data may be outdated and potentially compromised, requiring users to revert to older versions

Engineering Contradiction:

Improvedata integrityVSAvoidtime to restore data

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by continuously capturing and storing data changes in a write-through cache and maintainance log before any failure occurs. This allows the system to have pre-prepared data at any point in time ready for immediate restoration, eliminating the need to revert to outdated backup versions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system creates a copy of data changes in a write-through cache that mirrors the production volume. This copy mechanism allows restoration to any point in time by replaying or rolling back through the maintained logs, providing granular restore options without relying on scheduled backups.

Inventive Principle:

Principle #26Copying

2Reliability

If scheduled backups are performed, then data protection is provided, but substantial additional processing is required to bring the IT system back to where it was before the failure

Engineering Contradiction:

Improvedata protectionVSAvoidprocessing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system performs self-service by automatically maintaining a continuous write-through cache and transaction logs that track all data changes. When restoration is needed, the system can automatically replay or rollback through these logs without requiring substantial manual processing, making the restoration process efficient and automated.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of periodic scheduled backups, the system maintains continuous data protection through a write-through cache that continuously captures data changes. This continuous action eliminates gaps between backups and allows restoration to any specific point in time, improving both reliability and processing efficiency.

Inventive Principle:

Principle #20Continuity of useful action

3Loss of time

If the most recent backup data is used, then restoration is faster, but the data may be partially compromised (e.g., infected by a virus)

Engineering Contradiction:

Improverestoration timeVSAvoiddata compromise

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The system implements feedback by maintaining a transaction log that records all data changes with timestamps. This allows the system to identify and rollback to any previous state before a compromise occurred, providing the ability to select a safe restoration point while minimizing restoration time through automated log replay.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary action by continuously maintaining point-in-time snapshots through the write-through cache and transaction logs. This preparation allows immediate restoration to any previous state without having to perform time-consuming analysis or manual recovery processes.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If Point-in-Time instances with PTVV and CDP log are created, then continuous data protection and granular restore options are enabled, but the system complexity increases

Engineering Contradiction:

Improvecontinuous data protectionVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system applies segmentation by dividing the virtual volume into chunks and maintaining separate Point-in-Time instances with individual PTVV and CDP log structures. This modular approach allows continuous data protection through multiple granular snapshots while managing complexity through organized, reusable components that can be independently maintained.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8225146B2Method for implementing continuous data protection utilizing allocate-on-write snapshots

Publication Date: 2012.07.17 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

The present disclosure is directed to a method for providing continuous data protection for a virtual volume (VV). The method may comprise conceptually dividing the VV into a plurality of same sized chunks; preserving contents of the VV at a specified time; creating a Point in Time (PiT) instance for the VV at the specified time, comprising: a PiT Temporary Virtual Volume (PTVV) for storing modifications to the VV subsequent to the specified time, wherein data stored in the PTVV is prohibited from been overwritten; a re-allocation table for providing read access to a most recent version of each of the plurality of chunks of the VV; and a Continuous Data Protection (CDP) log for providing read access to a historic version of a chunk stored in the PTVV; and updating the PiT instance when a chunk of the plurality of chunks of the VV is being modified.