Consider the operation of a jukebox. Each table has a jukebox terminal where cus

Question

Consider the operation of a jukebox. Each table has a jukebox terminal where
customers can feed coins to play songs (50 cents apiece, three for a dollar). Prior
to the iPod era, the queue to hear your songs in a busy restaurant could be quite
long, sometimes longer than the average dining time, in fact.
Discuss the various disk scheduling algorithms as methods of selecting the
order in which to play the requested songs. Be sure to consider the advantages
and disadvantages of each method in terms of fairness, probability that each diner
will get to hear their songs, ease of implementation, and any other important
issues that you feel should be considered. You might note that multiple diners
would sometimes request the same song.

Explanation / Answer

Answer :

Answer :

SSTF
The process requests after request, go to the closest request in the work queue, regardless of direction
reduces total seek time compared to FCFS
Advantages
It exploits locality of disk requests
Has higher throughput
Disadvantages
It don’t always know what request will be fastest
No existence starvation

FCFS :

In facs perform operations in order requested and no reordering of work queue.There will be no starvation: every request is serviced and poor performance.This doesn’t provide fastest service
Advantages :
This is easy to implement
This has good fairness
Disadvantages:
This cannot exploit request locality
Increases average latency
And decreasing throughput

SCAN
It goes from the outside to the inside servicing requests and then back from the outside to the inside servicing requests. and repeats this over and over.
It also reduces variance compared to SSTF.
Advantages
This has locality to be known
Has bounded waiting
Disadvantages
Process in the middle get better service
Might miss locality SSTF could exploit

C-SCAN
This algorithm is commonly used in unix.The processes moves inwards servicing requests until it reaches the innermost process, then jumps to the outside process of the disk without servicing any requests. and repeats this over and over.

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