FastGC: Accelerate Garbage Collection via an Efficient Copyback-based Data Migration in SSDs

Copyback is an advanced command contributing to accelerating data migration in garbage collection (GC). Unfortunately, detecting copyback feasibility (whether copyback can be carried out with assurable reliability) against data corruption in the traditional copyback-based GC causes an expensive performance penalty. This paper first explores copyback error characteristics on real NAND flash chips, then proposes a fast garbage collection scheme called FastGC. It utilizes copyback error characteristics to efficiently detect copyback feasibility of data instead of transferring out all valid data for detecting. Experiment results in the SSDsim show the proposed FastGC greatly promotes write response time and read response time by up to 44.2% and 66.3% respectively, compared to the traditional copyback-based GC.