#52: An Enhanced I/O Model for Modern Storage Devices

While originally designed for disk drives, the read/write I/O model has provided a common storage abstraction for decades, regardless of the type of storage medium. Devices are becoming increasingly complex, however, and the constraints of the old model have compelled the standards bodies to develop specialized interfaces such as the Object Storage Device and the Zoned Block Commands protocols to effectively manage the storage. While these protocols have their place for certain workloads, there are thousands of filesystems and applications that depend heavily on the old model. It is therefore compelling to explore how the read/write mechanism can be augmented using hints and stream identifiers to communicate additional information that enables the storage to make better decisions. The proposed model is applicable to all types of storage devices and alleviates some of the common deficiencies with NAND flash and Shingled Magnetic Recording which both require careful staging of writes to media.