$1$

$3.$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 $2000M\frac{B}{s},$ and the data transfer rate of the disk is $100M\frac{B}{s}.$ It takes $0\mathrm{.}1ms$ 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.

Use the SCAN algorithm to schedule the I$/$O requests. $(5$ points$)$

Assume the system without cache. Calculate the total data access time ignoring the overhead and considering the memory hierarchy. $(15$ points$)$

$\backslash$table$[[\backslash$table$[[$Fil$],[$e$]],$Track,Size$],[1,90,10$MB$],[2,132,20$MB$],[1,90,10$MB$],[3,62,15$MB$],[4,115,6$MB$],[2,170,20$MB$],[5,11,10$MB$],[6,28,11$MB$]]$