ABSTRACT

Although main memories are becoming larger, there are still many large databases that cannot fit entirely in main memory. In addition, because main memory is larger and processing is faster, new applications are storing and displaying image data as well as text, sound, and video. This means that the data stored can be measured in terabytes. Few main memories hold a terabyte of data. So data still have to be transferred from a magnetic disk to main memory. Such a transferral is called a disk access.