Practical Issues in Designing of Garbage Collection for Solid States Drives

Abstract

Abstract-Due to out-of-place update property of NAND flash memory, garbage collection is required for NAND flash memory based SSDs (Solid-State Drives). In this paper, we discuss some practical issues on developing the garbage collection scheme. First, both efficiency and longevity should be considered together for garbage collection design. To this end, we present simple and effective victim block selection, hot/cold page classification, and free block management schemes. Second, the spatial and temporal overhead of garbage collection should be small for being employed on real systems. Finally, we discuss how to make use of the internal architecture of SSDs for garbage collection design. We implemented new garbage collection scheme that considers these all on real SSD platform. Through extensive experiments, we show that the proposed garbage collection scheme provides a good efficiency as well as expands the longevity of SSDs.