Denser and faster silicon integration has only exacerbated the problem of moving data to and from the storage subsystem. With applications getting larger and becoming more data-centric, the I/O subsystem has become a compelling target of optimization. Our research is examining techniques for bringing the right data to the right place at the right time towards reducing I/O latencies. In addition, storage virtualization is becoming central to hosting centers to isolate data centric services from each other. We are examining feedback control for QoS management at all levels of the storage hierarchy. Finally, with the I/O subsystem contributing to a significant portion of the overall power budget at data centers, we are looking to optimize the energy consumption of large disk arrays.