Non-Volatile Flash Table Storage for SSD Data Integrity

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Solution Overview

Problem

Existing storage systems employing physically-addressed SSDs face challenges in reliably preserving flash block management tables during power interruptions, leading to data corruption and increased initialization delays due to the lack of power backup for system memory and the need for time-consuming metadata reconstruction.

Innovation Solution

A storage system design that includes a CPU subsystem with a physically-addressed SSD, a non-volatile memory module for maintaining flash tables, and a PCIe switch, which maintains flash tables in non-volatile memory to avoid reconstruction upon power interruption, ensuring data integrity and reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If flash block management tables are maintained in volatile system memory, then access speed is improved, but data reliability deteriorates during power interruptions

Engineering Contradiction:

Improveaccess speedVSAvoiddata reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

A non-volatile memory module is introduced as an intermediary between the volatile system memory and the flash storage. This intermediary maintains a copy of the flash block management tables, allowing the system to quickly access data from volatile memory while ensuring reliability through the non-volatile backup that persists during power interruptions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The flash block management tables are copied from the volatile system memory to a non-volatile memory module. This copying mechanism ensures that critical management data is preserved even when power is interrupted, allowing the system to recover without reconstructing the tables from scratch.

Inventive Principle:

Principle #26Copying

2Reliability

If power backup is added to preserve flash tables, then data integrity is improved, but device complexity increases

Engineering Contradiction:

Improvedata integrityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of implementing expensive and complex battery-backed volatile memory or sophisticated power management systems, the invention uses a simple non-volatile memory module that inherently preserves data without requiring active power backup. This approach achieves data integrity with minimal added complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If metadata reconstruction is performed upon power-up, then data recovery is achieved, but initialization time increases

Engineering Contradiction:

Improvedata recoveryVSAvoidinitialization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The flash block management tables are preliminarily saved to non-volatile memory during normal operation before power interruptions occur. This preliminary action ensures that when power is restored, the system can immediately retrieve the tables from non-volatile memory without performing time-consuming reconstruction operations.

Inventive Principle:

Principle #10Preliminary action

4Loss of information

If flash blocks are frequently erased for updates, then data freshness is improved, but flash memory lifetime deteriorates

Engineering Contradiction:

Improvedata freshnessVSAvoidflash memory lifetime

Core Design Contradiction:

Loss of informationVSDuration of action of stationary object

Solution Approach 1:

The management tables that require frequent updates are extracted from the flash memory and maintained separately in non-volatile memory. This separation allows the flash memory to be used primarily for stable data storage, reducing the frequency of erase operations on flash blocks and thereby extending the overall lifetime of the flash memory.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10037272B2Storage system employing MRAM and array of solid state disks with integrated switch

Publication Date: 2018.07.31 AVALANCHE TECHNOLOGY INC

AI summary

A storage system includes a central processing unit (CPU) subsystem including a CPU, a physically-addressed solid state disk (SSD) that is addressable using physical addresses associated with user data, provided by the CPU, to be stored in or retrieved from the physically-addressed SSD in blocks. Further, the storage system includes a non-volatile memory module, the non-volatile memory module having flash tables used to manage blocks in the physically addressed SSD, the flash tables include tables used to map logical to physical blocks for identifying the location of stored data in the physically addressed SSD. Additionally, the storage system includes a peripheral component interconnect express (PCIe) switch coupled to the CPU subsystem and a network interface controller coupled through a PCIe bus to the PCIe switch, wherein the flash tables are maintained in the non-volatile memory modules thereby avoiding reconstruction of the flash tables upon power interruption.