Time taken to transfer the four successive sectors


#1

Consider a disk which has an average time of 30 ns and rotational rate of 360 rpm each track of disk has 512 sectors each of size 512 bytes. What is the time taken to transfer the four successive sectors. ?


#2

Given Data,
Average seek time = 30ns
Rotation rate = 360 RPM
Number of sector = 512
Sector capacity = 512 Bytes

Here we have to find disk access time of 4 sector i.e 4 * 512B = 2048 B
We know data transfer rate is 1536KB/sec
i.e 1 B data can be transferred in 11536×10311536×103 sec
i.e 2048 B can be transferred in 20481536×103sec=0.00133sec20481536×103sec=0.00133sec

Now 1 rotation is done in 1616 sec, so Avg rotation latency is 112112 sec i.e 0.0833 sec

As we know Disk access time = Avg seek time + Avg rotation latency + Data transfer rate
DAT = 30ns + 0.0833 sec + 0.00133 sec
we can neglect avg seek time as its too small
Therefore Disk Access time = 0.0846 secs