Recently, remarkable development of NAND flash technology makes possible the advent of SSD (solid-state-device) that is considered to replace traditional HDD, due to its potential benefits such as low-power usage and reliability. in this paper, we present a hybrid file system, called, N-hybrid. whose primary objective is to put together attractive features of both HDD and SSD, to construct a large-scale, virtualized address space in a cost-effective way. N-hybrid was designed to make use of SSD's high I/O performances, while providing a flexible internal structure to utilize excellent sequential performance of existing file systems. to optimize the limited space capacity of SSD partition, N-hybrid allows to define several data sections whose extent size can differ from each other. such a pre-determined extent size enables to define a data section in such a way to minimize the wasted hole of an extent, by closely matching a multiple of extent size to the file size to be allocated in the data section. several experiments were conducted to verify the performance of N-brid.