SSD Auto-Delete Feature for Read Threshold Management

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Solution Overview

Problem

Persistent storage devices, such as SSDs, face performance degradation and increased bandwidth consumption due to unnecessary data movement and garbage collection when nearly full, as they lack native awareness of invalid data and fail to promptly delete unused data, leading to reduced read/write IOPS and flash media endurance.

Innovation Solution

Implementing an auto-delete feature in SSDs that invalidates data when the number of read operations reaches a host-specified threshold, allowing for efficient garbage collection and reducing unnecessary data movement by specifying the expected number of reads during data writing, thereby reserving bandwidth for host I/O access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If garbage collection is performed frequently to delete invalid data, then storage efficiency is improved, but bandwidth consumption increases and IOPS decrease

Engineering Contradiction:

Improvestorage efficiencyVSAvoidIOPS

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by having the host device proactively send deletion notifications to the storage device before garbage collection is needed. This advance notice allows the storage device to prepare for deletion operations, reducing the urgency and frequency of reactive garbage collection, thereby lowering bandwidth consumption and preserving IOPS while maintaining storage efficiency.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If data is moved during garbage collection, then invalid data is deleted, but write amplification increases and flash media endurance decreases

Engineering Contradiction:

Improvedata managementVSAvoidflash media endurance

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent extracts the deletion notification function from the storage device and places it in the host device. This allows the host to identify and notify about invalid data before it accumulates, enabling the storage device to delete data in-place without requiring extensive data movement operations, thereby reducing write amplification and preserving flash media endurance.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If the storage device performs automatic deletion, then bandwidth is reserved for host I/O, but device complexity increases

Engineering Contradiction:

Improvebandwidth availabilityVSAvoiddeletion management

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent inverts the traditional approach by having the host device (rather than the storage device) take the initiative in identifying and notifying about invalid data. This inversion simplifies the storage device's deletion management complexity while reserving bandwidth for host I/O operations, as the storage device only needs to process deletion notifications and perform straightforward deletion operations.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP4198745B1Automatic deletion in a persistent storage device

Publication Date: 2024.10.23 SAMSUNG ELECTRONICS CO LTD

Figure 1
Figure 2A~2B
Figure 2C

AI summary

A system and method for automatic deletion in a persistent storage device. In some embodiments, the method includes: receiving, by a persistent storage device, a first read command, for a first logical block of data; determining that a total number of read operations, for the first logical block of data, equals or exceeds a first threshold value; and in response to determining that the total number of read operations, for the first logical block of data, equals or exceeds the first threshold value, arranging for deletion of the first logical block of data from the persistent storage device.