SSD Controller Dummy Command Generation for MDTS Support

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Solution Overview

Problem

Solid state drive (SSD) storage devices face challenges in supporting high values of maximum data transfer size (MDTS) without impacting the device controller or affecting other parameters, as large commands complicate exception scenarios and require increased buffers and costs.

Innovation Solution

The SSD advertises a higher MDTS than it can handle, splits large commands into dummy commands for processing, and delivers completion messages to the host device once all dummy commands are processed, allowing for transparent support of large command sizes without affecting internal components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the SSD advertises a higher MDTS to the host device, then the capability and flexibility of the storage device is improved, but the device complexity and cost increase due to requiring larger buffers and internal databases

Engineering Contradiction:

ImproveMDTS capabilityVSAvoidinternal structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments large commands exceeding the actual MDTS into multiple smaller dummy commands that fit within the device's actual processing capacity. The controller divides a large command into N smaller commands, processes them sequentially, and aggregates their completions to present as a single command completion to the host, thereby supporting advertised high MDTS without requiring corresponding large internal buffers

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dummy commands as intermediary elements between the host's large commands and the device's actual processing capability. These dummy commands act as a translation layer, converting host-side large command requests into multiple manageable internal operations without requiring the device to physically support the full advertised MDTS capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the SSD supports very large commands, then the capability and flexibility is improved, but the reset duration is extended and may violate the NVMe standard

Engineering Contradiction:

Improvecommand size capabilityVSAvoidreset duration

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of moving object

Solution Approach 1:

By segmenting large commands into multiple smaller dummy commands, the patent ensures that no single command exceeds the device's actual processing capacity. This segmentation allows the device to maintain shorter reset durations for each individual dummy command while still supporting large overall data transfers through aggregation of multiple smaller operations

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary splitting of large commands into dummy commands before processing begins. This preliminary action allows the device to prepare and queue multiple smaller commands that can be executed sequentially, ensuring that reset operations remain within NVMe standard time limits while still handling large data transfers

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the SSD requires larger buffers and internal databases to support high MDTS values, then the command processing capability is improved, but the area and cost of the storage device increase

Engineering Contradiction:

Improvecommand processing capabilityVSAvoidbuffer memory size

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent segments large data transfer commands into multiple smaller dummy commands, each fitting within the device's actual buffer capacity. This allows the device to process large overall data transfers using its existing smaller buffers, eliminating the need to increase buffer size while maintaining high productivity for large command operations

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates multiple copies (dummy commands) of portions of the original large command, processing them sequentially through the existing buffer infrastructure. This copying approach allows the device to handle larger effective command sizes without requiring proportionally larger physical buffers, as each dummy command uses the same buffer resources in sequence rather than requiring simultaneous capacity

Inventive Principle:

Principle #26Copying

Data Source

PatentUS10901624B1Dummy host command generation for supporting higher maximum data transfer sizes (MDTS)

Publication Date: 2021.01.26 SANDISK TECHNOLOGIES LLC

AI summary

The present disclosure generally relates to systems and methods for executing commands that are larger than the maximum data transfer size (MDTS) on a data storage device. The data storage device advertises to the host device a MDTS that is higher than the actual MDTS that the data storage device can actually handle. If the data storage device receives a command that is equal to or less than the actual MDTS, then the data storage device processes the command normally. If the data storage device receives a command that is greater than the actual MDTS, but with less than or equal to the advertised MDTS, the data storage device splits the command into a plurality of dummy commands for processing. Once all of the dummy commands have processed, the data storage device delivers a completion message to the host device.