NAND Flash Boot Pre-Read for Retention-Induced Read Retry
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Solution Overview
Problem
Mobile devices experience significant performance degradation due to read retry operations caused by the retention characteristics of NAND flash memory during the first storage device read operation after a long power-off period.
Innovation Solution
A storage system and method that includes a pre-read operation during booting to adjust the optimal read voltage of non-volatile memory devices by transmitting history level update messages and performing pre-read operations to set the optimal read level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the storage device uses NAND flash memory with retention characteristics, then data can be stored without power, but read performance degrades after long power-off periods due to optimal read voltage changes
Solution Approach 1:
The patent performs a pre-read operation during the system booting section to search for and set the optimal read voltage before normal operations begin. This preliminary action prevents performance degradation during subsequent read operations after long power-off periods, resolving the contradiction between data retention and read reliability.
2Measurement precision
If the storage device performs read retry operations to handle voltage drift, then read accuracy improves, but system boot time increases due to additional operations
Solution Approach 1:
The patent performs the optimal read voltage search and setting operation during the system booting section as a preliminary action. By completing the voltage optimization before normal operations, the system avoids time-consuming read retry operations during runtime, thus improving read voltage accuracy without significantly impacting system boot time.
Solution Approach 2:
The storage device autonomously performs the pre-read operation to determine and set its own optimal read voltage during booting. This self-service approach eliminates the need for host intervention and read retry operations, improving both read voltage accuracy and system efficiency.
3Productivity
If the host checks for history level update messages during booting, then read performance is optimized, but communication overhead increases between host and storage device
Solution Approach 1:
The storage device autonomously generates and transmits history level update messages to inform the host about optimal read voltage changes. This self-service mechanism allows the host to make informed decisions about pre-read operations without requiring complex continuous monitoring protocols, thus improving system boot speed while keeping communication overhead manageable.
Data Source
AI summary
A method of booting a storage system includes performing device booting of a storage device including a non-volatile memory device, determining whether a history level update message indicating that a read failure or a read retry has occurred in the non-volatile memory device is transmitted from the storage device to a host during the device booting, and requesting, by the host, the storage device to perform a pre-read operation to adjust the optimal read level of the non-volatile memory device according to the history level update message. The pre-read operation is performed during a system booting section of the storage system.