Abstract: Taking advantage of green energy is becoming increasingly popular, however, when it comes to the storage I/Os, where storage devices usually schedule nodes based on the intensity of the storage workload, the irregular fluctuations of green energy lead to the mismatch of peaks and valleys between green energy and storage workloads, which increases the difficulty of scheduling storage resources. To address this issue, a tiering-cooperative energy-efficient scheme, called MixSave, is proposed. It efficiently tiers NVM and SSD and replicates data among them based on their performance and energy characteristics, achieving both high performance and large capacity. MixSave customizes the energy-saving strategies for each layer and tunes them cooperatively between layers, allowing MixSave to reduce overall energy usage. The workload-driven strategy is used by the NVM layer, which is used for caching, to ensure the best performance, and the number of active NVM devices depends on the storage workload. Meanwhile, the SSD layer employs a green energy-oriented strategy to conserve traditional energy, and the number of active SSD devices will be proportional to the amount of green energy supplied. Evaluation results show that, when compared to energy-save-unaware approaches, MixSave degrades performance by less than 4% and saves traditional energy by 73%~80% and 55%~61% under light and heavy workloads, respectively.

Key words: Storage System, Hierarchical Storage, Non-Volatile Memory, Storage Energy Saving, Green Energy

摘要： 新能源的应用已成为一种趋势，但具体到存储I/O领域，存储设备通常会根据存储负载的强度进行节点调度，而不规则波动的新能源和存储负载之间存在波峰波谷错位匹配的问题，增加了存储设备的调度难度。为此，提出了一种针对NVM-SSD混合存储介质的分级协同节能方案MixSave，采用负载驱动缓存层与新能源驱动数据层的分级协同节能策略，提升了新能源能效比。基于NVM和SSD存储介质的性能与能耗特点，MixSave采用NVM-SSD的高性价比分级存储架构，为用户提供高性能、大容量存储服务，并且通过副本保证数据可靠性。NVM作为缓存层采用负载驱动型方案，以保证性能为优先目标，即根据负载变化动态调整高功耗状态的NVM设备数量，满足负载需求；SSD作为数据层采用新能源驱动型节能方案，以提升新能源利用率为目标，根据新能源的变化动态调整SSD启用数量，进行缓存数据同步与预取。测试表明，与未采取节能措施的标准方案相比，MixSave性能下降不超过4%，在轻负载模式下，MixSave可节省73%~80%的传统能源，在重负载模式下，可节省55%~61%的传统能源。

关键词: 存储系统, 分级存储, 非易失性存储, 存储节能, 新能源