In Proceedings of CASCON, 2014.
Flash-based solid state drives (SSDs) are increasingly becoming a
popular choice as a storage device within database management
systems and key-value stores alike. SSDs offer fast throughput and
low latency access to data, but their price-per-byte cost often makes
them uneconomical for exclusive use, especially in the era of big data
workloads. A common solution to this problem is to augment existing
database systems by adding smaller SSDs that target only
performance-critical areas. We believe this hybrid approach to be a
Rather than simply extending existing systems with SSDs, in this work we completely re-architect how a key-value database operates in a hybrid storage setting with both small but fast SSDs and slower but high-capacity HDDs. We formulate an accurate I/O cost model to study how popular key-value stores behave under several varying representative workloads. Based on these studies and taking a holistic approach, we design a system that dynamically optimizes the data layout and access strategy that leverages the strengths of each available storage medium.