#68: Andromeda: Building the Next-Generation High-Density Storage Interface for Successful Adoption

Open Channel describes a new interface to Solid State Drives (SSDs) which promises to increase usage of SSDs’ raw bandwidth from 40% to 95%, increase user-visible flash capacity from 50%-70% to 99%, increase I/O bandwidth by 3x and reduce per-GB hardware cost by 50%. Despite many proposals and implementations proving these benefits, industry has seen limited adoption and no standards body has integrated the concept. One of the largest hurdles to adoption is that the proposed changes permeate every layer in the storage stack, from device firmware to application. To reap the benefits, we need not only an end goal, but a pragmatic approach to introducing these changes to one or two layers at a time. We present relevant information about host and drive architecture, the expected use cases for Open Channel, and a general-purpose, maintainable end target for Open Channel. The final architecture refactors Flash Translation Layer into Log-Management, handled in the host, and NAND Management, handled in the drive. This consolidates repeated software algorithms, and retains media-specific functionality in the drive. The results of this design set up the storage community to innovate in traditionally independent areas. With a new interface in place, host-side software developers can apply a wide variety of software and technologies to further optimize their storage logs, and firmware and drive designers can focus on improvements in media management and density improvements.