Abstract
Tape is used widely in high reliability storage system. This paper introduces a storage system named Ro-RAT (Read only RAID-Tape-Library) which can be used in geological exploration storage. Tape is used as storage medium in Ro-RAT. Due to the sequence access to tape devices, a disk cache is used to reduce access time. Base on the study of the accessing characteristic, a new replacement algorithm called 2Q/F is introduced. The cache objects in 2Q/F are files, compared to pages in 2Q. As the files have different length, 2Q/F considers not only the access frequency of cache objects but also the size. To evaluate the performance of 2Q/F algorithm, trace-driven simulation experiments were taken. Compared to LRU and 2Q, 2Q/F improves hit rate for about 15% in Ro-RAT system.