Utilizing segment partitioning scheme for hybrid address spaces

Although the technology of flash memory is rapidly improving, SSD usage is still limited due to the high cost per storage capacity. In such a case, improving the storage utilization is the critical issue to achieve the desirable system performance. In this paper, we propose an extent-based allocation scheme for hybrid storage solutions, called MatBall (Matrix and extent-based allocation), whose objective is to increase space utilization of SSD partition in the hybrid file system by reducing fragmentation overhead. In MatBall, to consume the remaining spaces as much as possible posterior to file allocations, I/O units (extents) of the hybrid file system are recursively partitioned into segments in the subsequent level and further file allocations are performed in units of the partitioned segments. The performance measurement with IOzone shows that the hybrid file system using MatBall enables to produce higher bandwidth over ext2 installed on HDD and SSD.