Java Reference
In-Depth Information
8.3 Using the specifications for the disk drive given in Exercise 8.2, calculate the
expected time to read one entire track, one sector, and one byte. Show your
calculations.
8.4 Using the disk drive specifications given in Exercise 8.2, calculate the time
required to read a 10MB file assuming
(a) The file is stored on a series of contiguous tracks, as few tracks as pos-
sible.
(b) The file is spread randomly across the disk in 4KB clusters.
Show your calculations.
8.5 Assume that a disk drive is configured as follows. The total storage is ap-
proximately 1033MB divided among 15 surfaces. Each surface has 2100
tracks, there are 64 sectors/track, 512 bytes/sector, and 8 sectors/cluster. The
disk turns at 7200 rpm. The track-to-track seek time is 3 ms, and the average
seek time is 20 ms. Now assume that there is a 512KB file on the disk. On
average, how long does it take to read all of the data on the file? Assume that
the first track of the file is randomly placed on the disk, that the entire file lies
on contiguous tracks, and that the file completely fills each track on which it
is found. Show your calculations.
8.6 Using the specifications for the disk drive given in Exercise 8.5, calculate the
expected time to read one entire track, one sector, and one byte. Show your
calculations.
8.7 Using the disk drive specifications given in Exercise 8.5, calculate the time
required to read a 10MB file assuming
(a) The file is stored on a series of contiguous tracks, as few tracks as pos-
sible.
(b) The file is spread randomly across the disk in 4KB clusters.
Show your calculations.
8.8 A typical disk drive from 2004 has the following specifications.
3
The total
storage is approximately 120GB on 6 platter surfaces or 20GB/platter. Each
platter has 16K tracks with 2560 sectors/track (a sector holds 512 bytes) and
16 sectors/cluster. The disk turns at 7200 rpm. The track-to-track seek time
is 2.0 ms, and the average seek time is 10.0 ms. Now assume that there is a
6MB file on the disk. On average, how long does it take to read all of the data
on the file? Assume that the first track of the file is randomly placed on the
disk, that the entire file lies on contiguous tracks, and that the file completely
fills each track on which it is found. Show your calculations.
3
To make the exercise doable, this specification is completely fictitious with respect to the track
and sector layout. While sectors do have 512 bytes, and while the number of platters and amount of
data per track is plausible, the reality is that all modern drives use a zoned organization to keep the
data density from inside to outside of the disk reasonably high. The rest of the numbers are typical
for a drive from 2004.
