L2P Table Backup for Storage Controller Data Recovery

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Solution Overview

Problem

The conventional data backup method for storage devices with rewritable non-volatile memory modules fails to maintain the correctness of the logical-to-physical (L2P) table during sudden power-offs, leading to reduced accuracy in data reconstruction due to incomplete backup of the L2P table.

Innovation Solution

A data backup method that records trim marks in the L2P table, updates trim marks and the table based on trim and garbage collection commands, and performs periodic backups to the rewritable non-volatile memory module, ensuring accurate data recovery even after power failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the L2P table is stored only in memory (RAM) for quick access, then the speed of L2P table updates and access is improved, but the reliability of data is reduced because the L2P table disappears after power-off and cannot reflect the latest trim commands

Engineering Contradiction:

ImproveL2P table access speedVSAvoidL2P table data reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies preliminary action by periodically backing up the L2P table from memory to the non-volatile memory module before power-off events occur. The controller executes backup operations at predetermined intervals or when specific conditions are met, ensuring that the latest L2P table state (including trim command updates) is preserved in non-volatile storage before it can be lost

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism by maintaining two copies of the L2P table: one in volatile memory (RAM) for fast access and updates, and another in non-volatile memory for persistent storage. The controller acts as an intermediary that synchronizes these two copies, transferring updated L2P table data from RAM to non-volatile memory at appropriate intervals, thus bridging the speed-reliability gap

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the L2P table is backed up to non-volatile memory after every trim command, then the reliability of data recovery is improved, but the productivity of the system is reduced due to frequent write operations

Engineering Contradiction:

Improvedata recovery accuracyVSAvoidsystem operation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements periodic action by backing up the L2P table to non-volatile memory at predetermined intervals rather than after every trim command. The controller determines whether to execute a backup operation based on time-based thresholds or operation-count thresholds, performing backups periodically to balance data reliability with system productivity by avoiding excessive write operations

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies parameter changes by dynamically adjusting the backup frequency based on system conditions. The controller monitors parameters such as the number of trim commands received, time elapsed since last backup, and system workload, and adjusts the backup timing accordingly to optimize the balance between data reliability and operational efficiency

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If physical addresses are cleared immediately upon receiving trim commands, then the consistency of L2P table is improved, but the reliability of data recovery is reduced when power-off occurs before backup

Engineering Contradiction:

ImproveL2P table consistencyVSAvoiddata reconstruction accuracy

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies preliminary action by backing up the L2P table state to non-volatile memory before physical addresses are cleared in response to trim commands. By periodically saving the L2P table that still contains the original physical address mappings, the system preserves recovery information that can be used to reconstruct accurate data mappings even after power-off events

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by maintaining a backup copy of the L2P table in non-volatile memory that serves as a safety buffer against data loss. This backup acts as a cushion that protects the system from the harmful effect of premature power-off events, allowing accurate data recovery by restoring from the backed-up L2P table state

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS10372619B2Data backup method, data recovery method and storage controller

Publication Date: 2019.08.06 SHENZHEN EPOSTAR ELECTRONICS LTD

AI summary

A data backup method is provided. The data backup method includes maintaining a logical-to-physical table (L2P table) in a memory, where the L2P table records a plurality of physical addresses respectively corresponding to a plurality of first logical addresses and a plurality of trim marks; receiving a trim command, wherein the trim command indicates that data stored in one or more second logical addresses is invalid; according to the trim command, not clearing physical addresses respectively corresponding to the second logical addresses in the L2P table, and changing trim marks respectively corresponding to the second logical addresses from a first bit value to a second bit value; and when a predetermined condition is met, updating the L2P table according to the trim marks, and storing the updated L2P table into a rewritable non-volatile memory module.