SSD vs Magnetic Disks: Making the right choice

Abstract

We will, in this thesis, closely investigate the performance of SSDs and magnetic disks. Looking at physical attributes of these two disk technolo- gies, we will try to give an understanding of how they perform in dif- ferent scenarios based on real workloads. Based on what we learn from investigating the performance in these scenarios, we will try to get an un- derstanding of what performance issues the different storage technologies faces. We will look at how optimizations in Operating System (OS) and at application-level have an impact on SSDs and magnetic disks, as well as what we can do to achieve best possible performance.

In our benchmarks, we show that early generation SSD suffer from write amplification, and will, because of that, have problems achieving good performance on random write operations. By introducing a log-based file system, we see that we can remove the effect of write amplification received by random write operations, and give us a more stable perfor- mance. We discuss, and benchmark, possible alternatives for optimizing existing applications for magnetic disks, by introducing SSDs, as an alter- native to magnetic disks as storage device. By going from high-end mag- netic disks to SSDs, we see that we, in some cases, can achieve orders of magnitude better performance, without changing application level code.