Data Transfer

Question

I have a normal Doubt Consider a Scenario:-

1. Total number of block are = K

Total number of records per block = P

Size of record = B bytes

And we need to transfer all the blocks in memory.

Avg rotation latency = R

Seek time = S

Block transfer rate = Rp

So while calculating the total access time:-

Do we need to add seek time and rotational latency corresponding to each record or only once ????

and for transfer time = P*B*K / Rp right ??

or Answer depends on number of disk access per block i.e.

If i say that for accessing every block i need one disk access so therefore i need to add seek time and rotation latency and transfer time for every block rt? else in one access i can transfer everything???

Plz correct me if i am wrong?

Answer 1

Do we need to add seek time and rotational latency corresponding to each record or only once ????

So if your reader is on that particular track of disk from where you want to read data so no need to seek time and if the reader is also on that particular block also so no rotational delay which is a very rare scenario.

and for transfer time = P*B*K / Rp right ??

or Answer depends on number of disk access per block i.e.

Transfer time will be simple block transfer rate = Rp*k (k= number of disk block read)  as the computer read entire block and is not bothered about what's inside

If i say that for accessing every block i need one disk access so therefore i need to add seek time and rotation latency and transfer time for every block rt? else in one access i can transfer everything???

 Usually, data is scattered across disk so each time it is new rotational and seek time is required, but if you are reading all data from adjacent block then no need to add