Designing A True Direct-Access File System With Devfs

We present DevFS, a direct-access file system embedded completely within a storage device. DevFS provides direct, concurrent access without compromising file system integrity, crash consistency, and security. A novel reverse-caching mechanism enables the usage of host memory for inactive objects, thus reducing memory load upon the device. Evaluation of an emulated DevFS prototype shows more than 2x higher I/O throughput with direct access and up to a 5x reduction in device RAM utilization.