taking all sorts of factor like cost and storage capability into account, people mostly use tertiary storage equipment like tape library or optical disk library as the primary storage medium to store massive data . at present, a three layer storage system composed of main memory, disk and tertiary storage has already been the primary storage structure of massive data 從成本和存儲(chǔ)容量等因素綜合考慮,目前人們大都采用將磁帶庫、光盤庫等第三級(jí)存儲(chǔ)設(shè)備作為海量數(shù)據(jù)的主要存儲(chǔ)介質(zhì),并與主存、磁盤一起構(gòu)成一個(gè)三級(jí)的存儲(chǔ)系統(tǒng)作海量數(shù)據(jù)的存儲(chǔ)結(jié)構(gòu)。