3. There are 8 file requests in the system. Their track numbers and data size are listed in the following table. There are some duplicated requests. If the file names are the same, they are the same file. The hard drive disk spins at 7200rpm. The data transfer rate of the main memory is 2000MB/s, and the data transfer rate of the disk is 100MB/s. It takes 0.1ms to traverse one track. For example, it takes 1ms to move from track 50 to track 60 . If the last visited track is 50 and the direction of the arm is increasing. 1. Use the SCAN algorithm to schedule the I/O requests. (5 points) 2. Assume the system without cache. Calculate the total data access time ignoring the overhead and considering the memory hierarchy. ( 15 points)