What's Up with the Storage Hierarchy?

Ten years ago, Jim Gray observed that flash was about to replace magnetic disks. He also predicted that the need for low latency would make main memory databases commonplace. Most of his predictions have proven accurate. Today, who can make predictions about the future of the storage hierarchy? Both main memory and storage systems are undergoing profound transformations. First, their design goals are increasingly complex (reconfigurable infrastructure at low latency, high resource utilization and stable energy footprint). Second, the status quo is not an option due to the shortcomings of existing solutions (memory bandwidth gap, inefficiency of generic memory/storage controllers). Third, new technologies are emerging (hybrid memories, non-volatile memories still under non-disclosure agreements, near-data processing in memory and storage). The impact of these transformations on the storage hierarchy is unclear. Yet, they raise interesting research questions.