Consider the bitmap representation of the free$-$space map, where for each block

in the file, two bits are maintained in the bitmap. If the block is between $0$ and

$30$ percent full the bits are $00,$ between $30$ and $60$ percent the bits are $01,$

between $60$ and $90$ percent the bits are $10,$ and above $90$ percent the bits are $11.$

Such bitmaps can be kept in memory even for quite large files.

i Outline two benefits and one drawback to using two bits for a block, instead

of one byte as described earlier in this chapter.

ii Describe how to keep the bitmap up to date on record insertions and

deletions.

iii Outline the benefit of the bitmap technique over free lists in searching for

free space and in updating free space information.