The introduction of flash storage solid-state drives (SSDs) has added considerable innovation to HPC I/O and storage system design. And for good reason; SSDs provide over an order of magnitude faster bandwidth and orders of magnitude faster IOPS compared to hard disk drives (HDDs). But for any given capacity, enterprise SSDs also cost 10 times more than nearline HDDs, and HPC storage typically requires both high performance and high capacity. This performance/capacity trade-off has made tiering from a relatively low capacity, high performance storage tier, to a more cost-effective high capacity tier, a current design focus in HPC storage. This panel session surveys how HPC storage developers and architects have addressed this challenge. The panelists are the technical leaders drawn from a broad representation of HPC storage organizations each of whom has solved this performance/capacity challenge in surprisingly unique and individual ways.