Metadata Fragmentation in Distributed Encoded Storage

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Solution Overview

Problem

Distributed encoded storage systems face challenges in efficiently storing and retrieving data due to the high cost and reduced durability of metadata storage on expensive, low-latency solid state disks (SSDs), which are used to maintain metadata responsiveness and redundancy.

Innovation Solution

The solution involves encoding metadata into fragments and storing these fragments on backend storage elements, while using low-latency frontend storage elements only for metadata fragment identifiers, allowing quick retrieval and maintaining the same redundancy level as the encoded data fragments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If metadata is stored on expensive SSDs to ensure high responsiveness, then system responsiveness is improved, but storage cost increases

Engineering Contradiction:
Improvemetadata access speedVSAvoidstorage cost
Core Design Contradiction:
SpeedVSQuantity of substance

Solution Approach 1:

The patent segments metadata into multiple fragments and distributes them across backend storage elements. Only fragment identifiers (not the full metadata) are stored on frontend SSDs, reducing the quantity of expensive storage required while maintaining fast access capability through the fragmented structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the essential identifying information (fragment identifiers) from the complete metadata and stores only these extracted elements on expensive frontend SSDs. The full metadata fragments are removed from frontend storage and placed on cheaper backend storage, significantly reducing SSD usage while preserving system responsiveness.

Inventive Principle:
Principle #2Taking out (Extraction)

2Quantity of substance

If metadata is stored on backend storage elements with data, then storage cost is reduced, but system responsiveness deteriorates

Engineering Contradiction:
Improvestorage costVSAvoidmetadata access speed
Core Design Contradiction:
Quantity of substanceVSSpeed

Solution Approach 1:

Metadata is segmented into fragments distributed on backend storage, but the critical fragment identifiers remain on fast frontend storage. This segmentation allows the system to use slower backend storage for bulk metadata while maintaining fast access paths through the identifier cache on frontend SSDs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by storing different types of information in different locations: fragment identifiers (small, frequently accessed) are stored on fast frontend SSDs, while full metadata fragments (large, less frequently accessed) are stored on slower backend storage. Each location optimizes for its specific access patterns.

Inventive Principle:
Principle #3Local quality

3Reliability

If metadata is duplicated across multiple datacenters for redundancy, then reliability is improved, but storage cost and complexity increase

Engineering Contradiction:
Improvemetadata redundancyVSAvoidstorage resources
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent segments metadata into fragments that can be independently distributed and replicated across datacenters. This segmentation enables more efficient redundancy strategies where not every fragment needs to be replicated everywhere, reducing the total storage overhead for achieving reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fragment identifier structure serves multiple functions: it uniquely identifies metadata fragments, enables fast lookup on frontend storage, and facilitates distributed storage and replication across multiple datacenters. This multi-functionality reduces the need for separate redundancy mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentUS10749958B2Reduced storage of metadata in a distributed encoded storage system
Publication Date: 2020.08.18 WESTERN DIGITAL TECHNOLOGIES INC
  • US10749958B2 patent drawing
  • US10749958B2 patent drawing
  • US10749958B2 patent drawing

AI summary

A data object can be encoded into a plurality of encoded data fragments and stored on backend storage elements in a distributed encoded storage system. The identifiers and metadata corresponding to each encoded fragment of the data object can be stored in a single metadata unit, which is stored on the backend as encoded fragments. The identifiers of the metadata fragments can be associated with the data object and stored on a low latency frontend storage device. Thus, the amount of metadata per data object stored on expensive low latency frontend storage is reduced to the fragment identifiers. The fragment identifiers can be quickly retrieved, and used to retrieve the identifiers and metadata corresponding to the encoded data fragments from the backend, for retrieval of the data object itself.