Statistical Placement on Disks

Abstract

The access pattern on each multimedia object can have very different characteristics. Some multimedia objects are more popular and they are more frequently accessed by more users. The user may concern the average access time on the objects. Thus, the storage systems can make use of the popularity of multimedia objects to optimize the average access time. Some objects need to be accessed at a higher data rate than the other objects. The users may concern the continuity of these objects. The storage systems may store the high data rate objects at the locations where data transfer rates are higher. The statistical placement methods place the multimedia objects according to the characteristics of their access patterns. We shall describe the frequency based placement or popularity based placement method which optimizes the mean access time as the performance metric in the next section. After that, we shall describe the bandwidth based placement which uses the object continuity as the performance metrics. When two placement methods are compared on the same storage system, each one of the methods may show better performance according to different metrics. System builder may choose the appropriate method according to the method that shows better performance in the preferred metrics. Thus, both placement methods have their significance.