Solid State Storage: Analysis And Evaluation of Fundamental Limitation of Write Performance

The continuous evolvement and improvement of Flash memory based storage devices in performance, reliability and cost, makes it a viable solution for applications that require high performance and reliability. However, in spite of large features that this type of storage devices provide, like high performance, low energy consumption, etc., compared to mechanical disks, it still has certain constraints which linked to the unique characteristics of NAND flash memory. NAND Flash memory has the virtue of erasing before writing operation, in which Garbage collection is needed for collecting invalid data. The process of Garbage collection is causing a performance degradation of SSDs, which leads to the possibility of writecliff phenomenon occurrence. This paper is going to investigate that phenomenon by benchmarking several Flash-based devices from different manufacturers, to find out how each device is capable of efficiently erasing all blocks without falling into the write-cliff. The principal finding of this research reveals that the occurrence of write-cliff is highly variable and complex, and it is depending on multiple variables that prevent finding a general mechanism for detecting how accurately each Flashbased device’s blocks are erased