OS Mass-Storage Structures

efficiency

enough storage space for data

storage overhead

time consumption overhead

LOOK

SCAN

C-SCAN

C-LOOK

can

cannot

must not

none of the mentioned

only I

only II

both I and II

neither I nor II

the total number of bytes transferred

total time between the first request for service and the completion on the last transfer

the total number of bytes transferred divided by the total time between the first request for service and the completion on the last transfer

none of the mentioned

performance, redundancy

performance, reliability

redundancy, performance

none of the mentioned

programmable interval timer

interrupt timer

programmable timer

none of the mentioned

destroyed blocks, high level formatting

bad blocks, partitioning

bad blocks, low level formatting

destroyed blocks, partitioning

each I/O device type

each I/O device address

each I/O device state

all of the mentioned

Every disk has to participate in every I/O request

Only one disk participates per I/O request

I/O cycle consumes a lot of CPU time

All of the mentioned