Abstract: With the high-speed development of application, the requirement for greater capacity, higher I/O speed, and better performance NAS device have been the study hotspot of network storage. To solve the above-mentioned issues, an iSCSI-based network attached storage server （iNAS: iSCSI-bases NAS） is designed. Firstly, iNAS can provide file I/O and block I/O service by iSCSI module, implementing the merging of NAS and SAN. Secondly, iNAS greatly improves I/O speed by the direct data acess （zero copy） between the RAID controller and the user memory. Thirdly, iNAS merges multi-RAID for a single storage pool by using a multi-stage striping device driver, implementing storage virtualization. The experiment shows that iNAS has ultra-high-throughput for file I/O and block I/O.