SSD Auxiliary Battery Power for Ungraceful Shutdown Recovery
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Solution Overview
Problem
Flash storage devices face challenges with ungraceful shutdowns (UGSD) due to power losses during operations, leading to uncertain data states and potential read errors upon power restoration.
Innovation Solution
The storage device incorporates a power management circuit and a rechargeable battery to detect power losses, send messages to the RAID controller, and supply emergency power to complete ongoing operations, thereby facilitating a graceful shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flash storage device operations are performed without additional power protection, then device complexity is reduced, but reliability deteriorates due to ungraceful shutdowns and uncertain data states
Solution Approach 1:
The patent introduces a battery as an intermediary power source between the host device and the flash storage device. The battery acts as a mediator that provides supplemental power during host power failures, allowing the flash storage device to complete ongoing operations gracefully. This intermediary component resolves the contradiction by adding reliability without requiring complex control logic within the flash storage device itself.
Solution Approach 2:
The patent implements beforehand cushioning by providing a battery that is预先 charged and ready to supply power when the host power fails. This prior cushioning ensures that the flash storage device has sufficient power to complete ongoing write operations and perform graceful shutdown procedures, preventing data corruption without requiring complex real-time power management within the storage device.
2Reliability
If write operations are performed in non-volatile memory, then data storage capability is improved, but reliability deteriorates due to long operation times making the device vulnerable to power loss
Solution Approach 1:
The battery provides beforehand cushioning by being pre-charged and ready to immediately supply power when host power fails during a write operation. This ensures that the flash storage device can complete the ongoing write operation to non-volatile memory without interruption, maintaining reliability despite the long duration of write operations.
Solution Approach 2:
The patent enables continuity of useful action by ensuring that write operations can complete uninterrupted even when host power fails. The battery maintains continuous power supply to the flash storage device during the extended write operation duration, allowing the operation to proceed to completion without power loss corruption.
3Reliability
If power loss protection mechanisms are implemented, then reliability is improved, but device complexity increases due to additional components and control logic
Solution Approach 1:
The battery serves as an intermediary that simplifies the power loss protection architecture. Instead of implementing complex power management logic within the flash storage device, the battery externally provides the necessary power cushioning, allowing the storage device to maintain simple control logic while achieving reliable power loss handling.
Solution Approach 2:
The battery provides self-service by autonomously supplying power during host power failures without requiring complex control logic in the flash storage device. The simple controller only needs to detect power failure conditions and switch to battery power, while the battery independently manages its own discharge to complete operations, reducing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively minimizes the effects of UGSD by allowing the storage device to complete operations using emergency power, ensuring data integrity and reducing the risk of read errors upon power restoration.
Implementation Method 1
The storage device includes a memory, a controller coupled to the memory, a power management circuit coupled to the memory and the controller, and a rechargeable battery coupled to the power management circuit
Data Source
AI summary
Aspects of a storage device, a host device, and a redundant array of independent disks (RAID) system including multiple storage devices and the host device are provided that provide power control and power loss handling. The host device and the storage devices in the RAID system may each include at least a memory, a controller coupled to the memory, and a power management circuit coupled to the memory and the controller. A storage device controller may receive rationed power from the host device or a RAID controller in the host device in response to a message from that storage device indicating a detected loss in supplied power. An amount of the rationed power is based on a program data rate of the storage device or a size of data from the host device or the RAID controller to be written to the memory. Thus, UGSDs may be detected and addressed.