Host Memory Patrol Read State Transition
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Solution Overview
Problem
In nonvolatile memory devices like flash memory, the patrol read process for error detection and correction is hindered when the device transitions to a power-saving mode or is powered off, as it cannot execute patrol read operations, affecting data retention and reliability.
Innovation Solution
A host device is designed to manage memory devices by transitioning them from an active state to a sleep state and back based on access times, allowing patrol read operations to be executed when necessary, and notifying the memory device to perform patrol read and refreshing tasks, ensuring data integrity and power savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the memory device transitions to a power-saving mode or is powered off, then power efficiency is improved, but patrol read operations cannot be executed, affecting data retention and reliability
Solution Approach 1:
The host device performs preliminary actions by transitioning the memory device to an active state before the patrol read operation is actually needed. The host monitors access patterns and proactively activates the memory device to ensure patrol read can be executed, rather than reacting after data retention issues arise. This resolves the contradiction by preparing the system in advance to maintain reliability while keeping power consumption low during normal operation.
Solution Approach 2:
The system implements feedback mechanisms where the host device monitors memory access patterns and adjusts the active/sleep state transitions accordingly. The host receives information about memory operations and uses this feedback to determine when to transition between states, ensuring patrol read operations are performed when necessary while maximizing power savings during idle periods. This feedback loop resolves the contradiction by dynamically balancing power efficiency and data reliability based on actual usage conditions.
2Reliability
If the memory device remains in active state continuously, then patrol read operations can be executed, but power consumption increases
Solution Approach 1:
Instead of continuous active state, the system employs periodic action by transitioning the memory device between active and sleep states based on access patterns. The host device monitors for a predetermined period whether the memory device is accessed, and only transitions to active state when necessary to perform patrol read operations. This periodic activation pattern resolves the contradiction by maintaining reliability through periodic checks while minimizing power consumption during extended idle periods.
Solution Approach 2:
The system applies dynamics by making the memory device state flexible and adaptive rather than fixed. The active/sleep state transitions are dynamically adjusted based on real-time access patterns and patrol read requirements. The host device dynamically determines when activation is necessary, allowing the system to adapt between power-saving mode and operational mode. This dynamic approach resolves the contradiction by allowing the system to optimize between power consumption and reliability based on actual operational conditions.
3Reliability
If the host device monitors access patterns continuously, then appropriate state transitions can be made, but system complexity increases
Solution Approach 1:
The host device performs self-service by autonomously monitoring access patterns and making state transition decisions without requiring complex external control systems. The host device independently tracks whether the memory device has been accessed within a predetermined period and automatically determines when to transition between active and sleep states. This self-service capability resolves the contradiction by simplifying the overall system architecture while maintaining reliable state management through straightforward monitoring and decision logic.
Data Source
AI summary
According to one embodiment, a controller of a host causes a memory device to transit from a first state that is an active state to a second state that is a sleep state in a case where there is no access to the memory device for a first time or more. The controller causes the memory device to transit from the second state to the first state in a case where there is no access to the memory device for a second time or more after the transition to the second state.