LHPC—Sycomore Aerospatiale MatraAs processors become more powerful and clusters larger, users will exploit this increased power to progressively run larger and larger problems. Today's datasets in biology, physics or multimedia applications are huge and require high performance storage sub-systems. As a result, the hot spot of cluster computing is gradually moving from high performance computing to high performance IO. The solutions proposed by the parallel file-system community try to improve performance by working at the kernel level to enhance the regular IO design or by using a dedicated Storage Area Network like Fiber Channel.We propose a new design to merge the communication network and the storage network at the best price. We have implemented it in OPIOM with the Myrinet interconnect: OPIOM moves data asynchronously from SCSI disks to the embedded memory of a Myrinet interface in order to send it to a remote node. This design presents attractive features: high performance and extremely low host overhead.