Improving write amplification in a virtualized and multimedia SSD system

摘要

Due to offering fast random-access disk I/O, it appears that solid-state drives (SSD), which is based on NAND flash memory, can suit well with the environment of cloud computing, especially for the cloud providing video streaming services. However, by investigating a practical virtual desktop system, where runs video streaming workloads, we find that importing this kind of SSDs into a virtualized system is not as simple as merely a mechanical replacement. Because a large proportion of disk I/O being included in the video streaming workload is write I/O, the inherent weaknesses of NAND flash memory, write amplification (WA), will be magnified in a guest operating system (OS). Worse, some useful remedies in a native OS become disabled or inefficient due to the interposition of hypervisor layer. This paper describes and analyzes these problems based on a practical virtual desktop system, and then proposes a tailor-made method to relieve them. By evaluating realistic user workloads and several typical benchmarks, the result shows that our method can effectively improve these problems in our virtualized SSD system.