RAID Fast Rebuild Mechanism Using Block Valid Data Indication

Solution Overview

Problem

Existing RAID systems face inefficiencies in rebuild operations due to increased time for degraded volumes, impact on host access performance, and lack of awareness about used blocks during rebuilds, leading to prolonged data vulnerability and performance degradation.

Innovation Solution

A fast rebuild mechanism with a background initialization function that identifies and rebuilds only blocks with valid data, utilizing a RAID controller and IO controller to detect and flag valid data blocks, allowing for selective rebuilding and maintaining metadata to indicate rebuild status.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional rebuild operations are performed on all blocks in a RAID system, then data redundancy is restored, but rebuild time increases significantly and host access performance degrades

Engineering Contradiction:

Improvedata redundancy restorationVSAvoidrebuild time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the rebuild operation by dividing the virtual disk into individual blocks and identifying only those blocks that contain valid user data. The rebuild process then operates selectively on these identified blocks rather than performing a full disk rebuild, thereby reducing rebuild time while maintaining data redundancy restoration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by performing rebuild operations only on the necessary subset of blocks that contain valid data, rather than rebuilding the entire virtual disk. The block valid data indication serves as a marker to identify which blocks require rebuilding, enabling the system to perform exactly the necessary work without excess operations.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If traditional rebuild operations are performed on all blocks in a RAID system, then data redundancy is restored, but host access performance degrades due to increased disk access operations

Engineering Contradiction:

Improvedata redundancy restorationVSAvoidhost access performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent segments the rebuild operation by dividing the virtual disk into individual blocks and identifying only those blocks that contain valid user data. The rebuild process then operates selectively on these identified blocks rather than performing a full disk rebuild, thereby reducing rebuild time while maintaining data redundancy restoration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by performing rebuild operations only on the necessary subset of blocks that contain valid data, rather than rebuilding the entire virtual disk. The block valid data indication serves as a marker to identify which blocks require rebuilding, enabling the system to perform exactly the necessary work without excess operations.

Inventive Principle:

Principle #16Partial or excessive action

3Loss of time

If background initialization is implemented to make virtual disk available sooner, then system availability improves, but additional complexity is introduced in tracking and managing block validation status

Engineering Contradiction:

Improvevirtual disk availability timeVSAvoidblock validation tracking complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent extracts the validation status information into a separate metadata structure (block information portion with valid block data indication) distinct from the actual user data. This separation allows the system to track which blocks contain valid data without complicating the data storage structure itself, enabling background initialization while maintaining manageable complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary metadata structure (block information portion) that mediates between the actual data blocks and the rebuild operation. This intermediary stores the valid block data indication and enables the controller to make informed decisions about which blocks need rebuilding, simplifying the overall management of block validation status.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8751862B2System and method to support background initialization for controller that supports fast rebuild using in block data

Publication Date: 2014.06.10 DELL PROD LP

AI summary

A fast rebuild mechanism that includes a background initialization mechanism. The fast rebuild mechanism allows a RAID controller to be made aware of what blocks are actually in use so that only those blocks are rebuilt after a disk drive failure. The fast rebuild mechanism also includes functionality for an IO controller (such as storage controller) to detect whether a block has stored data to indicate that the block has valid data when the block is accessed.