Q$3.($a$)$ Suppose that the disk head has just completed a request at track $125$ and is now

positioned serving a request at track $133.$ The queue of requests has the

following sequence:

$190,50,122,145,65,175$

$($i$)$ Show all the tracks traversed starting from the track $133$ based on the

Shortest Service Time First $($SSTF$)$ scheduling algorithm and compute

the total number of tracks traversed.

$(4$ marks$)$

$($ii$)$ A disk scheduling algorithm suggested that the disk arm is restricted to

scan in one direction only. It services all outstanding requests until it has

no more requests in that direction. The arm changes to the opposite

direction and the scan begins again. What is the name of this suggested

policy?

$(2$ marks$)$

$($iii$)$ Calculate the total number of tracks traversed starting from the track $133$

using the disk scheduling algorithm that you have named earlier in Q$3$

$($a$)($ii$).$ Use the same sequence of track requests given in Q$3($a$).$

$(4$ marks$)$

$($b$)$ Figure $1$ shows File B allocated in a disk where the index block is stored in

block number $15.$

Figure $1$

$($i$)$ According to Figure $1,$ identify the type of file allocation method used.

$(2$ marks$)$

$($ii$)$ Fill up the Block Number of the index block shown in Figure $1.$

$(3$ marks$)$help