SD Storage Array: Development and Characterization of a Many-device Storage Architecture

Transactional workloads have storage request streams consisting of many small, independent, random requests. Flash memory is well suited to these types of access patterns, but is not always cost-effective. This thesis presents a novel storage architecture called the SD Storage Array (SDSA), which adopts a many-device approach. It utilizes many flash storage devices in the form of an array of Secure Digital (SD) cards. This approach leverages the commodity status of SD cards to pursue a cost-effective means of providing the high throughput that transactional workloads require. Characterization of a prototype revealed that when the request stream was 512B randomly addressed reads, the SDSA provided 1.5 times the I/O operations per second (IOPS) of a top-of-the-line solid state drive, provided there were at least eight requests in-flight. A scale-out simulation showed the IOPS should scale with the size of the array, provided there are no upstream bottlenecks.MAS