Research about Two-Level Cache Base on SDRAM in RAID Controller

In RAID system, the disk cache for improving RAID system performance is a very important aspect. Two-level cache displays superior performance in comparison to single cache and is effective in temporal and spatial locality. The proposed cache system in this paper consists in two levels. The first level cache is a set associative cache with small block size whereas the second level cache is a fully associative cache with large block size. In this paper, a RAID disk cache model is presented that is located on a disk controller, which can improve disk input and output time especially in a large capacity disk cache and maintain consistency effectively. The aim is to show, in terms of hit ratio and service time, that the two-level cache structure presented in this paper is in fact much improved.