The ANSI Object-based Storage Device (OSD) standard is a major step toward enabling explicit applicationawareness in storage systems behind a standard, fullyinteroperable interface [3]. In this paper, we explore a particular flavor of application-awareness, that of database applications. We describe the design and implementation of a database-aware storage system that uses the OSD interface not only as a means to access data, but also to permit explicit communication between the application and the storage system. This communication is significant, as it enables our storage system to transparently optimize data placement and request scheduling. We demonstrate that OSD makes it practical to improve storage performance in these ways without exposing proprietary disk drive parameters to application code, and without labor-intensive, fragile parameter measurement.