Split Non-Operational Power States for Data Storage Devices
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Solution Overview
Problem
Existing data storage devices face challenges in minimizing power state transition costs and efficiently using power states, particularly during short idle durations, which can lead to increased write amplification and reduced non-volatile memory endurance.
Innovation Solution
The implementation of split, non-operational power states for data storage devices allows for internal transitions without advertising these changes to the host, adjusting advertised power state parameters to guide the host's power decisions, and utilizing a timer to dynamically manage the transition to the lowest power state, thereby reducing transitional energy costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the device transitions to the lowest power state (PS4) immediately upon host request, then power consumption is reduced, but transitional energy costs increase and non-volatile memory endurance decreases due to frequent flush operations
Solution Approach 1:
The patent segments the non-operational power states into two distinct states: PS3 (first non-operational state) and PS4 (second non-operational state). PS3 is designed for rapid transitions with short entry/exit latency, while PS4 is designed for deep power savings with longer latency. This segmentation allows the device to choose the appropriate state based on idle duration, avoiding the need to immediately transition to PS4 and thereby reducing transitional energy costs and wear on non-volatile memory.
Solution Approach 2:
The patent introduces dynamic power state management where the device autonomously determines which power state to enter based on the detected idle duration. The controller monitors idle time and dynamically selects between PS3 and PS4, adjusting the power state transition strategy according to actual usage patterns rather than following a fixed protocol. This dynamic approach optimizes the balance between power savings and transition costs.
2Use of energy by stationary object
If the device transitions to PS4 state with longer entry/exit latency, then power consumption is reduced, but the time required to resume operation increases
Solution Approach 1:
By segmenting power states into PS3 (low latency) and PS4 (low power), the system can match the latency characteristics to the actual needs of the host. For short idle periods, PS3 provides quick resume capability. For longer idle periods, PS4 provides maximum power savings. This segmentation resolves the contradiction by offering a latency-power tradeoff rather than a single fixed characteristic.
Solution Approach 2:
The patent changes the power state parameters dynamically based on idle duration thresholds. When idle time exceeds a predetermined threshold, the device transitions from PS3 to PS4, altering the entry/exit latency parameter to achieve lower power consumption. This parameter change strategy allows the system to optimize between latency and power consumption based on actual operational conditions.
3Reliability
If the device frequently flushes data to non-volatile memory to maintain endurance, then memory lifespan is extended, but write amplification increases and power consumption rises
Solution Approach 1:
The patent implements preliminary action by maintaining data in volatile memory during the PS3 state before transitioning to PS4. The controller delays the flush operation until necessary, rather than continuously writing to non-volatile memory. This preliminary retention strategy reduces write amplification and power consumption while still ensuring data persistence when the device wakes from PS4, as the data can be quickly reloaded from volatile memory if needed.
Data Source
AI summary
The present disclosure generally relates to split, non-operational power states for a data storage device. The data storage device can transition between the split, non-operational power states without advertising the transition to the host device. The power state parameters that are advertised to the host device are adjusted such that the host device is guided to the correct power decision based on the advertised power and duration. By splitting the non-operational power states, the data storage device does not incur additional transitional energy costs for short idle durations.