第三级存储器中的磁带选择算法

Tape selection algorithms in tertiary storage

提出最多请求个数优先和最小请求优先磁带选择算法,用于优化磁带装载次序.为了进一步降低磁带交换代价,在如上两个算法中引入权重因子,得到加权磁带选择算法使得在线磁带卸载之前服务更多请求.实验表明,最多请求个数优先和最小请求优先磁带选择算法以及相应的加权算法均优于经典的Round-Rob in方法,尤其加权最多请求个数优先磁带选择算法效率最高.

Two tape selection algorithms are proposed： the maximum request number first （MaxNF） algorithm and the minimum request size first （MinSF） algorithm. Weight factors are used in the above schedule algorithms to favor the online tapes so that the requests for online tapes are served first before the online tapes are ejected. The weighted tape selection algorithms are called wMaxNF and wMinSF, respectively. By comparison to the Round - robin policy, the experimental results show that the four tape selection algorithms have higher efficiency of data access in tertiary storage. The efficiency of wMaxNF is highest of all the algorithms. Furthermore, the optimal weight factors can be derived from experiments.