Solid-state disks (SSDs) have the potential to revolutionize the storage system landscape. However, there is little published work about their internal organization or the design choices that SSD manufacturers face in pursuit of optimal performance. This paper presents a taxonomy of such design choices and analyzes the likely performance of various configurations using a trace-driven simulator and workload traces extracted from real systems. We find that SSD performance and lifetime is highly workloadsensitive, and that complex systems problems that normally appear higher in the storage stack, or even in distributed systems, are relevant to device firmware. 1

Conventional wisdom holds that storage is not a big contributor to application performance on mobile devices. Flash storage (the type most commonly used today) draws little power, and its performance is thought to exceed that of the network subsystem. In this paper we present evidence that storage performance does indeed affect the performance of several common applications such as web browsing, Maps, application install, email, and Facebook. For several Android smartphones, we find that just by varying the underlying flash storage, performance over WiFi can typically vary between 100 % to 300 % across applications; in one extreme scenario the variation jumped to over 2000%. We identify the reasons for the strong correlation between storage and application performance to be a combination of poor flash device performance, random I/O from application databases, and heavy-handed use of synchronous writes; based on our findings we implement and evaluate a set of pilot solutions to address the storage performance deficiencies in smartphones. 1