階層式多媒體資料之儲存管理

Abstract

階層式儲存架構主要是將 cache的觀念應用在資料儲存管理上, 以較便宜 但傳輸速度較慢的儲存器為主要資料庫, 而以存取快速的磁碟當伺服器, 儲存較常被使用的資料供永使用者讀取. 當所要擷取的資料不在磁碟上 時, 需將資料從資料庫中載入. 因此要有較好的取代原則來決定當磁碟滿 載時哪些資料該被取代, 以減少到儲存資料庫載入資料的次數.在本論文 中, 我們提出一些取代方法, 讓使用者所要的資料儘量能在伺服器中找到 而減少載入的動作.此外我們也提出一個儲存管理模式,將資料儘可能地存 放於連續的磁碟區, 以減少存取時的搜尋時間, 降低取代時所需的時間及 動作. A hierarchical storage manager uses tertiary storage such as tape or CD jukeboxes for archive data, and fast magnetic disks as a local file server to cache frequently accessed data. If the requested data is not on the disks, the server should download it from the jukeboxes and may replace an old one. In this thesis, we propose four data replacement policies: popularity, partitioned LRU+LFU, partitioned LRU+LFU with popularity, partitioned LRU with popularity. The popularity replacement policy has a better performance than the existing policies. We also propose a storage management strategy which can reduce the seek time in retrieval and the CPU cost in allocation and deallocation of disk space.