Sector Signature Patterns for Detecting Write Loss in Data Storage

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Solution Overview

Problem

Data storage systems face challenges in detecting lost writes and inconsistencies, as existing error detection and correction mechanisms are ineffective against these types of errors, leading to potential data corruption.

Innovation Solution

Implementing a sector signature transition controller that uses a plurality of sector signature patterns, including horizontal and diagonal parity values, to embed and update data signatures, and performs data integrity checks using metadata records and pattern-to-key lookups, allowing for efficient detection and correction of data integrity errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional error detection and correction codes (EDAC) are used to detect bit flips and sector failures, then data integrity against these errors is improved, but lost writes and inconsistencies remain undetected

Engineering Contradiction:
Improvedata integrityVSAvoiderror detection capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments data into slices and assigns sector signatures to specific sectors within each slice. This segmentation allows the system to track writes at the sector level while maintaining slice-level integrity checks, enabling detection of lost writes that traditional EDAC cannot detect.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces sector signatures as an intermediary mechanism between the data storage system and error detection. These signatures act as a mediator that tracks sector-level changes and enables detection of lost writes, bridging the gap between traditional EDAC and comprehensive data integrity verification.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If sector signature patterns are embedded with every data slice to enable integrity checks, then detection of lost writes is improved, but computational burden and system complexity increase

Engineering Contradiction:
Improvelost write detectionVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies partial action by performing integrity checks only on sectors that have been modified or are suspected of containing lost writes. Rather than checking every sector in every slice, the system selectively verifies sectors based on write operations and signature mismatches, reducing computational overhead while maintaining detection capability.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent changes parameters by using compact sector signature patterns (e.g., 16-bit or 32-bit values) instead of comprehensive checksums. This parameter change reduces the computational burden of generating and verifying signatures while maintaining sufficient discrimination capability to detect lost writes.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If multiple sector signature patterns are used to replace embedded patterns on writes, then detection accuracy is improved, but write operation overhead increases

Engineering Contradiction:
Improveintegrity check accuracyVSAvoidwrite operation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-generating and storing multiple sector signature patterns in advance. When a write operation occurs, the system can quickly select and apply the appropriate pre-computed signature without performing complex calculations during the write, thus maintaining high accuracy while minimizing write overhead.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses periodic action by cycling through a sequence of sector signature patterns for different writes to the same slice. This periodic pattern replacement provides comprehensive coverage over time, ensuring that lost writes are detected while distributing the computational load across multiple operations rather than concentrating it in a single expensive verification.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentUS11150988B1Metadata pattern to detect write loss/inconsistencies of optimized-write-once operations
Publication Date: 2021.10.19 EMC IP HLDG CO LLC
  • US11150988B1 patent drawing
  • US11150988B1 patent drawing
  • US11150988B1 patent drawing

AI summary

Sector signature patterns with sector signature values and sector signature parity values are embedded with data slices. A new pattern is embedded with a slice each time the slice data is updated. The patterns are selected in order such that every sector signature value and sector signature parity value changes when a new pattern is embedded. A separate metadata record such as a key is maintained to indicate which pattern has been embedded with the slice. A data integrity check is performed by comparing the embedded sector signature parity values with the metadata record and/or performing a pattern-to-key lookup.