Buffer Power Management for Storage Sleep Mode Latency
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Solution Overview
Problem
Current storage devices face increased power consumption and latency when entering deep sleep mode due to the need to write meta-data from the buffer memory to non-volatile memory, and the standby power of the buffer memory contributes to higher power usage.
Innovation Solution
A storage device that sets the power mode of the buffer memory based on predetermined conditions, either powering it off or switching to a low-power mode when entering deep sleep mode, to reduce the time and power required for writing meta-data to the non-volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If power of buffer memory is blocked when entering deep sleep mode, then power consumption is reduced, but time and power required to write meta-data to non-volatile memory increases
Solution Approach 1:
The controller determines whether to block power to the buffer memory before entering deep sleep mode by evaluating conditions such as the amount of meta-data to be written and the expected sleep duration. This preliminary assessment allows the system to proactively decide on the power management strategy, avoiding the need to write meta-data after power is blocked, thereby resolving the contradiction between reducing power consumption and minimizing data write time
2Reliability
If power of buffer memory is not blocked, then meta-data can be retained, but standby power consumption increases
Solution Approach 1:
The system dynamically adjusts the power state of the buffer memory based on real-time conditions including the amount of meta-data present, the duration of the sleep mode, and the frequency of wake-up operations. By making the power management strategy adaptive rather than static, the system can retain meta-data when necessary while minimizing standby power consumption by blocking power when conditions permit, thus resolving the contradiction between reliability and energy efficiency
3Use of energy by stationary object
If buffer memory is set to power-off mode, then power consumption is reduced, but data must be written to non-volatile memory increasing operation time
Solution Approach 1:
Before transitioning the buffer memory to power-off mode, the controller performs a preliminary evaluation of the dump time required to write meta-data to non-volatile memory and compares it against the expected sleep duration. This advance planning ensures that data is written only when it will be retained long enough to justify the power savings, thereby maintaining productivity while reducing power consumption
4Reliability
If buffer memory operates in self-refresh mode, then data is retained with low power, but still consumes more power than complete power-off
Solution Approach 1:
The controller dynamically selects between self-refresh mode and complete power-off mode for the buffer memory based on the amount of meta-data that needs to be retained and the expected duration of the sleep mode. When minimal data needs to be retained or the sleep duration is short, complete power-off is selected to minimize power consumption. When larger amounts of data must be retained for longer periods, self-refresh mode is selected to balance data retention reliability with power consumption, thus resolving the contradiction between these two parameters
Data Source
AI summary
A storage device includes a non-volatile memory including a plurality of non-volatile memory cells, a buffer memory configured to temporarily store write data to be written to the non-volatile memory or read data read from the non-volatile memory, and a controller configured to receive a sleep mode signal from an external host. When the sleep mode signal is received by the controller, the controller is configured to block a first power supplied to the non-volatile memory and set the buffer memory to one of a first mode in which a second power is blocked from being supplied to the buffer memory and a second mode in which the buffer memory operates with low power. The write data stored in the buffer memory is written to the non-volatile memory when the buffer memory is set to the first mode.