分散式點播系統下媒體資料的放置和負荷的動態平衡調節

Abstract

對一個媒體點播系統而言，有兩個主要的瓶頸︰第一個是硬碟，第二 個是網路。因此，為了能提供眾多的客戶和大量的資料，由許多電腦組合 而成的分散式系統是一個自然的解決方法。但是，分散式系統會產生各個 節點負荷不平均的問題。在本論文中，我們首先提出一個由每個影片的受 歡迎程度和每一個節點的容量及頻寬而得到的啟發性放置演算法。除此之 外，因為媒體點播系統具有動態的特性，因此我們進一步提出一個動態的 負荷平衡調節演算法，使系統中資料的放置能與每個影片受歡迎程度的改 變相配合。由模擬實驗顯示我們提出的方法反應良好，並且優於靜態的方 式。 There are two limited components for a multimedia-on-demand system. One isdisk I/O subsystem, the other is the networking system. Thus, for supportinga large customer base and a diverse archive of videos, the distributed multimedia server architecture that is constructed from personal computer is naturally a solution. However, the distributed environment suffer from load imbalance among each node. In this thesis, we first present a heuristicplacement algorithm based on the popularity of each video and the bandwidthand capacity of each node. In addition, because the dynamic characteristicof multimedia-on-demand system, we further propose a dynamic load balancingalgorithm to keep pace with the change of popularity of each video.Simulationresults show that the proposed algorithm is responsive well and is superiorto the static method.