Interrupted Write Protection for Commodity Storage Arrays

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Solution Overview

Problem

Database systems using commodity storage arrays lack interrupted write protection, leading to incomplete data writes due to software or hardware failures, which are not detectable in direct attached disks or software RAID systems.

Innovation Solution

A device driver and daemon system that generates intent logs for writes, stores them in non-volatile memory, and replicates them across nodes to ensure detection and recovery of interrupted writes, allowing for the identification and handling of incomplete data transfers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If commodity storage arrays (direct attached disks or software RAID) are used, then cost and accessibility are improved, but interrupted write protection is lost

Engineering Contradiction:

ImprovecostVSAvoidinterrupted write protection

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces an intermediary layer (device driver with intent log and daemon process) between the database system and commodity storage arrays. This intermediary provides interrupted write detection and protection capabilities that would otherwise only be available in proprietary storage systems, thereby resolving the contradiction by adding the missing reliability feature without changing the underlying commodity storage hardware.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The solution segments the write protection functionality into separate components: intent log generation, non-volatile storage of write status, and detection mechanisms. This segmentation allows the protection mechanism to be implemented independently on top of commodity storage, enabling reliable interrupted write detection while maintaining cost-effective storage hardware.

Inventive Principle:

Principle #1Segmentation

2Reliability

If proprietary storage systems with native interrupted write protection are used, then data integrity is improved, but cost and accessibility are worsened

Engineering Contradiction:

Improvedata integrityVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent copies the essential functionality of proprietary storage protection mechanisms into a software layer that works with commodity hardware. By implementing intent log generation and tracking in software rather than requiring specialized hardware, the solution achieves similar data integrity protection at lower cost, effectively copying the protective function without the proprietary storage overhead.

Inventive Principle:

Principle #26Copying

3Adaptability or versatility

If software RAID or direct attached disks are used, then flexibility and accessibility are improved, but detection of interrupted writes is lost

Engineering Contradiction:

ImproveflexibilityVSAvoidinterrupted write detection

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements a feedback mechanism where the device driver generates intent logs that track the status of ongoing writes, and the daemon process periodically checks these logs to detect interrupted writes. This feedback loop enables detection of write interruptions in flexible commodity storage systems, resolving the contradiction by adding monitoring capability without reducing system flexibility.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9665431B2Interrupted write protection with generic storage

Publication Date: 2017.05.30 TERADATA CORP

AI summary

A system and method providing interrupted write protection to a stand-alone commodity storage array utilized within a database system. The method identifies writes of data from the database system to the storage array requiring interrupt protection, and for each write, generates an entry for an intent log maintained within the database system. The log entries include a write identifier, storage device information associated with a write, and a write statues indication which are used to identify failed writes following a database system failure.