Research On Energy-aware Fault-tolerant Flash Storage Systems

Spaceborne detection can obtain more direct,comprehensive and accurate astronomical data.Providing massive storage for spaceborne applications is the urgent requirement of applying Big Data technologies to advance astronomy research.Spaceborne storage usually has the characteristics that workload fluctuates wildly,redundancy is highly required,and power consumption is strictly controlled.Existing research is difficult to meet above multi-constrained conditions.The thesis will research high-performance,low-power and fault-tolerant flash storage architecture for these applications according to their running environments and workload characteristics.The research mainly includes:(1)a fault tolerance mechanism of flash memory chip level is studied.The extensive use of SLC/MLC flash technology makes the current SSD have higher capacity and density,but the storage system in itself has a certain reliability issues.At the same time,the write overhead of parity calculation while using the traditional RAID scheme would not improve the reliability.To solve this problem,we propose a scheme that can use RAID technology at the SSD chip level.This scheme is designed and implemented,tested and validated on the Disk Sim simulator with SSD extension.By comparing our scheme with the traditional RAID5 scheme,it shows that the scheme designed in this thesis significantly improves the reliability of the storage system.This reliability lifting technique helps to provide a flash memory storage system for harsh environments,such as in a space environment and all spaceborne applications.(2)a flash memory chip level hybrid energy saving scheduling algorithm is studied.In order to improve the performance of small satellite's mass storage unit,a NAND flash technology is introduced into storage system to reduce power consumption while satisfying high performance.The technology combines the advantages of fast and low power consumption and static random access memory(SRAM)of NAND flash driver in RAID,which can effectively improve the storage performance of on-board computers on spacecraft.Then we used Disk Sim to simulate.The results show that the improvement of the traditional RAID5 mechanism can effectively reduce the energy consumption of the system while meeting the I/O requirements of space applications.Under the harsh conditions of performance,power and availability,the scheme can meet the needs of small satellite storage applications in space environment.(3)a flash memory device based on object storage is studied.By applying object-based storage,writing and amplification can be reduced to improve the efficiency of garbage collection.Simulation results show that this method can reduce data migration caused by update and reduce the resulting write operations,which not only reduce power consumption,but also improve storage device space utilization.