Micah Acinapura		DBS	Chapter 7

7.2

-Seek time is the time it takes for the hard disk to move it's heads to 
get the next piece of data.

-Rotational Latency is a delay in reading from the disk steming from the
fact that the disks are circular platters. Rotational latency is the time
you have to wait for the disk to rotate with the proper info under the head.

-The transfer time is the time it takes the hard disk to get the info off
the disk, throught the controller and onto the bus.

7.4

In this case you would want to store the data sequentially on the disk using 
concurrent block or sectors depening on the size. I was under the impression
that this was standard practice for most files not just large ones.

7.5
1) a. 50 sectors per track * 512 bytes per sector = 25,600 bytes per track.
   b. 2000 tracks per surface = 2000 * 25600 = 51,200,000 bytes per surface.
   c. 10 surfaces * 51,200,000 bytes per surface = 512,000,000 byter per disk.

2) 2,000

3) 312, 1024 are example block sizes. 256, 2048, 51,200 all seem fine to me.

4) (1/5400)/60 = 

5) (5400 * 25,600) / 60 = bytes per second = 2,304,000 bytes per second.


7.6

1) 10

2) 10,000

b) 1 surface. This is because we need to store 10,000,000 bytes 
	      but a surface can store up to    51,200,000 bytes

3) 5,120,000

4) The next surface is empty because we only need 1 surface to store
the whole thing. If all the head could read in parallel then, If page
one was stored on block 1 track 1, the we would have page two stored 
on block 1 track 1 of the next surface.

5) 10,000,000 bytes to read / 2,304,000 bytes read per second = 4.34 secs

6) block = 1024 bytes.
   10 record per block.

   each block = TransTime + avg rot lat + avg seek time
    12.3 msec = 0.5 msec  + 1.8 msec    + 10 msec


  12.3 msec per block * 10,000 blocks = 123 secs = seems to slow?