Consider a disk where seek time dominates rotational latency and transfer time. Hence, we only care about how many tracks need to seek over to service our requests. Cylinders on the disk are numbered from 0 (innermost) to 20 (outermost). The disk head currently resides on cylinder 8. Consider the start of servicing disk request to be time 0. Count time in number of seeks and calculate the number of seeks required to service the following requests under the given scheduling algorithms. Also calculate the average seek time per request. REQUEST NAME REQUEST ARRIVES CYLINDER REQUESTED A after 0 seeks 12 B after 0 seeks 4 C after 0 seeks 10 D after 0 seeks 2 E after 8 seeks 20 F after 8 seeks 3 G after 8 seeks 17 H after 14 seeks 4 Use (a) Shortest Seek First (SSF) algorithm and (b) Elevator algorithm (SCAN), considering the initial movement of the disk head to go inward from cylinder 8.
Consider a disk where seek time dominates rotational latency and transfer time. Hence, we only care about how many tracks need to seek over to service our requests. Cylinders on the disk are numbered from 0 (innermost) to 20 (outermost). The disk head currently resides on cylinder 8. Consider the start of servicing disk request to be time 0. Count time in number of seeks and calculate the number of seeks required to service the following requests under the given scheduling algorithms. Also calculate the average seek time per request.
REQUEST NAME REQUEST ARRIVES CYLINDER REQUESTED
A after 0 seeks 12
B after 0 seeks 4
C after 0 seeks 10
D after 0 seeks 2
E after 8 seeks 20
F after 8 seeks 3
G after 8 seeks 17
H after 14 seeks 4
Use (a) Shortest Seek First (SSF)
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