Flexible Storage Expansion via Logical Slicing

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Solution Overview

Problem

Conventional RAID systems require adding multiple disk drives to expand storage capacity, which limits scalability and necessitates reconfiguration, causing performance issues and write amplification in SSDs.

Innovation Solution

A method to add one or more physical storage devices to a data storage system by logically dividing them into slices, allowing for flexible expansion of storage capacity without reconfiguring existing erasure encoding groups, by selecting empty groups, designating spare slices, and potentially creating new groups or changing encoding schemes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If multiple disk drives are added to expand storage capacity in conventional RAID systems, then storage capacity is improved, but device complexity and reconfiguration requirements increase

Engineering Contradiction:

Improvestorage capacityVSAvoidreconfiguration complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent divides physical storage devices into multiple slices, allowing individual slices to be added to the storage system independently. This segmentation enables flexible capacity expansion without requiring addition of entire RAID groups, thus reducing reconfiguration complexity while maintaining storage capacity improvements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic slice allocation where new slices can be dynamically assigned to existing or new erasure encoding groups based on system needs. This dynamic approach allows the storage system to adapt to capacity requirements without fixed reconfiguration rules, reducing complexity compared to conventional static RAID group additions.

Inventive Principle:

Principle #15Dynamics

2Quantity of substance

If disk drives are added to existing RAID groups to expand capacity, then storage capacity is improved, but system performance deteriorates due to data movement

Engineering Contradiction:

Improvestorage capacityVSAvoidsystem performance

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

By segmenting storage devices into slices, the patent allows new capacity to be added as independent slices rather than requiring integration into existing RAID groups. This eliminates the need for data movement and rebalancing operations, maintaining system performance while expanding storage capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces erasure encoding groups as an intermediary layer between physical slices and logical storage volumes. This abstraction allows new slices to be added to the system without directly impacting existing data structures, avoiding performance-degrading data movement operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If disk drives are added to existing RAID groups to expand capacity, then storage capacity is improved, but write amplification increases reducing SSD useful life

Engineering Contradiction:

Improvestorage capacityVSAvoidSSD useful life

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The patent segments storage devices into independent slices that can be added without triggering reconfiguration operations. This eliminates write amplification caused by data redistribution, thereby preserving SSD useful life while still expanding storage capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary slicing of storage devices before they are added to the system. By pre-dividing devices into manageable slices with proper erasure encoding group assignments, the system avoids subsequent write amplification that would occur during runtime reconfiguration operations.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If fixed RAID group configuration is used to ensure data protection, then reliability is improved, but adaptability deteriorates

Engineering Contradiction:

Improvedata protectionVSAvoidstorage expansion flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent maintains data protection through erasure encoding groups while segmenting storage devices into slices. This allows flexible addition and removal of slices without compromising the integrity of existing erasure encoding groups, thus maintaining reliability while improving adaptability for storage expansion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic slice allocation to erasure encoding groups, allowing the system to adapt to changing storage requirements while maintaining data protection guarantees. New slices can be dynamically assigned to groups based on capacity needs without requiring reconfiguration of existing protected data structures.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11461023B1Flexible expansion of data storage capacity

Publication Date: 2022.10.04 EMC IP HLDG CO LLC

AI summary

Flexibly expanding the storage capacity of a data storage system by adding a single physical storage device or any number of disk drives to an existing storage system without the need to reconfigure existing erasure encoding groups of the system. The physical storage devices of a data storage system may be divided into a plurality of slices, and each slice may be a member of an erasure encoding group. Physical storage devices that are added to the data storage system may be divided into same number of slices and/to slices of a same size, which then may be added to existing erasure encoding groups, utilized as spare slices or left idle until all of the slices are integrated into the data storage system.