As the storage density and total storage capacity per die in flash memory keep increasing, the total power consumption and power density also increases. Furthermore, more flash memory dies are assembled in a storage device and system, which leads to even higher power consumption and heat generation. Thermal throttling is critical to protect the device from overheating and damage induced by high temperature. Thermal throttling is triggered after the device temperature reaches a preset throttling point. The data read and write performance will be downgraded to reduce the rate of heat generation. In this paper, a model predictive control (MPC) based thermal throttling management method was proposed. The simulation results show that this method can achieve efficient thermal throttling control such that the device temperature will not exceed the preset throttling point. However the proposed MPC based throttling enables a much smoother transition from the peak performance to the downgraded performance after throttling is triggerred, comparing to the traditional PID or bangbang control based throttling. The performance loss is minimized when using MPC based throttling. We also compared the performance transition and thermal behavior of the SSD by different throttling methods when the cooling environments changes suddently, such as the cooling fan fails.

Thermal Throttling by Model Predictive Control in Flash Memory

Paper Proceedings: https://asmedigitalcollection.asme.org/ISPS/ISPS2021/volume/84799

ASME 2021 Information Storage and Processing Systems (ISPS2021)

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