Keith A. Smith, Sun Microsystems

The Direct Access File System (DAFS) is a new, fast, and lightweight remote file system protocol. DAFS targets the data center by addressing the performance and functional needs of clusters of application servers. We call this the local file sharing environment. File access performance is improved by utilizing Direct Access Transports, such as InfiniBand, Remote Direct Data Placement, and the Virtual Interface Architecture. DAFS also enhances file sharing semantics compared to prior network file system protocols. Applications using DAFS through a user-space I/O library can bypass operating system overhead, further improving performance. We present performance measurements of an IP-based DAFS network, demonstrating the DAFS protocol's lower client CPU requirements over commodity Gigabit Ethernet. We also provide the first multiprocessor scaling results for a well-known application (GNU gzip) converted to use DAFS.