SSD Controller Emergency Evacuation Block for Power Loss Protection

Solution Overview

Problem

In solid-state drives (SSDs), the existing backup battery systems required for power loss data protection (PLP) are large and costly due to the high power consumption during sudden power shutdowns, necessitating a reduction in size and cost while maintaining data integrity.

Innovation Solution

The implementation of a memory system with a dedicated emergency evacuation block in the NAND, utilizing a backup battery to write volatile data into this block during power loss, allowing for subsequent restoration and writing into a non-volatile host write block upon reboot, thereby reducing power consumption during PLP processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a backup battery is used to write data from volatile memory to nonvolatile memory during sudden power shutdown, then data integrity is maintained, but the battery size and cost increase due to high power consumption

Engineering Contradiction:

Improvedata integrityVSAvoidbattery size

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent segments the nonvolatile memory into a host write block for normal operations and a dedicated emergency evacuation block for power loss protection. This segmentation allows the system to use only a portion of the nonvolatile memory for emergency data protection, reducing the power and battery capacity needed during sudden power shutdowns while maintaining data integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary actions by maintaining a mapping table in the controller that maps volatile memory addresses to host write block addresses before power loss occurs. This pre-established mapping enables the emergency evacuation block to be used efficiently without requiring complex real-time address translation during power loss events, reducing the computational power needed from the battery.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a backup battery is used to write data from volatile memory to nonvolatile memory during sudden power shutdown, then data integrity is maintained, but the battery cost increases due to high power consumption

Engineering Contradiction:

Improvedata integrityVSAvoidbattery cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the nonvolatile memory into a host write block for normal operations and a dedicated emergency evacuation block for power loss protection. This segmentation allows the system to use only a portion of the nonvolatile memory for emergency data protection, reducing the power and battery capacity needed during sudden power shutdowns while maintaining data integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the operational parameters by using the emergency evacuation block with modified write operations during power loss events. This parameter change reduces the power consumption requirement from the backup battery, allowing for a smaller, less expensive battery while still ensuring data integrity during sudden power shutdowns.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If write data is stored in volatile memory and then written to nonvolatile memory during normal operation, then data is persisted, but power consumption is high during sudden power shutdown

Engineering Contradiction:

Improvedata persistenceVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent segments the nonvolatile memory into a host write block for normal operations and a dedicated emergency evacuation block for power loss protection. This segmentation allows the system to use only a portion of the nonvolatile memory for emergency data protection, reducing the power and battery capacity needed during sudden power shutdowns while maintaining data integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The emergency evacuation block serves as an intermediary structure that receives data from volatile memory during power loss events. This intermediary block simplifies the power loss protection mechanism by providing a dedicated destination for emergency writes, reducing the computational overhead and power consumption compared to using the full host write block management system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11947400B2Memory system and controller

Publication Date: 2024.04.02 KIOXIA CORP

AI summary

In a memory system in an embodiment, in a case of normal operation, a control unit returns a write completion response upon completion of reception of write data from a host, and writes the write data into nonvolatile memory in a multiple values. In a case of unordinary power-off, changeover to operation using a backup battery is conducted and the control unit writes dirty data that is not completed in writing into the nonvolatile memory, into the nonvolatile memory with two values. When next boot, the control unit reads the dirty data from the nonvolatile memory into the volatile memory, and thereafter writes the dirty data into the nonvolatile memory in a multiple values.