Question

A disk has 20 surfaces (i.e. 10 double sided platters). Each surface has 1000 tracks. Each tracks has 128 sectors. Each sector can hold 64 bytes. The disk space allocation policy allocates an integral number of contiguous cylinders to each file,

a.) How many bytes are contained in one cylinder?

b.) How many cylinders are needed to accommodate a 5-Megabyte file on the disk?

c.) How much space is wasted in allocating this 5-Megabyte file?

Answer 1

To know that A cylendar has 15 tracks;

as per the given question 1 Track = 128 sectors
1 sector= 64 bytes
so,

1) 1 cylender= 15tracks
= 15*128*64 =122880 bytes or 122.88kb

2) for 5MB file to be recorded on a disk around 42 cylendars to be required

Expl: 1024*5--->?

122.88-->1 cyleendar

= 1024*5/122.88 = 41.6

3) so Wasted space is 322 bytes