Zhou and Co-Authors Examine Performance of Storage Systems in Latest Research

The TSYS School’s Yi Zhou and colleagues from Jinan University and Auburn University examine the performance of storage systems in their new research project.  As they explain, garbage collection running in the controller of 3D NAND flash-based solid-state disks plays a critical role in that performance, and solid-state disk manufacturers have developed various garbage collection solutions based on internal data movement to mitigate the impacts of garbage collection on request latency.  According to Zhou, “Due to the circuit characteristics of flash memory, existing internal data movement-based garbage collection strategies require that odd pages must be migrated to odd pages, and even pages to even pages. When migrating two consecutive pages with the same parity, the free page between the two migrated pages will be wasted after the migration is complete.”  As the study explains, this issue inevitably deteriorates the storage space utilization of flash memory, thereby degrading the overall performance of 3D NAND flash-based solid-state disks.  Zhou and his co-authors propose a parity-check garbage collection scheme to revamp solid-state disk performance by alleviating page waste during garbage collection.  Their investigation, which is set to appear in a future issue of IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, resulted in development of a parity-check unit to facilitate checking the parity of migrated valid pages and destination pages. Testing reveals that their solution dynamically adjusts the migration order of valid pages during the course of garbage collection and fundamentally averts page waste caused by the page parity restriction.  More specifically, their unit curtails the number of wasted pages by up to 91.4%, cuts back the number of garbage collection counts by up to 52.2%, and slashes average write response time by up to 77.8%.