DI-SSD: Desymmetrized interconnection architecture and dynamic timing calibration for solid-state drives

Abstract

NAND flash-based solid-state drives (SSDs) have long been architected in the way that the interconnections between a flash controller and the associated flash memory chips operate at a symmetric speed in both directions. However, this commonly accepted and widely used architecture is suboptimal to SSDs because reading flash cells is 10 to 20x faster than writing them. In response, we propose desymmetrized interconnection SSD architecture (DI-SSD) and dynamic timing calibration (DTC), which selectively push the flash-to-controller speed to the limit. We conduct comprehensive experiments including characterizing real SSD products, using industrial-strength IC test equipment to emulate a flash controller that adopts DTC, and simulating DI-SSD using simulators to demonstrate the benefits of our proposals.