Quiz 17.3

DIRECTIONS: Read each question carefully. Then click on the dot next to the answer that most closely fits the question. Try to answer all questions on this quiz and when you are done, click on the grade me button at the bottom.

Coverage: Section 17.6

  1. What do we call the storage method where a file is kept as sequence of disk blocks that are physically adjacent?
contiguous allocation
linked list allocation
block allocation

  1. Which of the following is not a good reason to choose contiguous allocation for a new disk system?
it is easy to implement
it is fast; given one sector it doesn't take much time to find the next
when a file needs to grow, all the sectors must be copied into a new block of free sectors

  1. What is one of the downsides to using linked list allocation?
it permits files to use up any and all available free sectors on a disk
it robs some memory space from each sector
it allows files to grow easily

  1. What happens if a file has been expanded many times in a linked list allocation disk system?
performance degrades since the disk will have to do lots of seeks
performance increases since the needed sectors are randomly scattered over the disk and hence equally likely to be nearby

  1. What is the process by which a file composed of widely scattered sectors is copied into a region of continguous sectors?
defragmentation
dealignment
disallocation

  1. What do we call a group of tracks that are all the same distance from the edge of the platter?
sector
cylinder
ring
track group

  1. Why is it good to try to store files in these groups of tracks?
it makes it easier to find the needed sectors when opening a file
it is faster to get at the files' sectors because the rotational delay is constant here
it cuts down on seek time since the read/write head never has to move

  1. What data structure must be maintained by the operating system that keeps files on a disk drive?
free sector list
pointers
table of cylinder groups

  1. How many read/write heads are there in a disk drive that has 5 platters, each of which is double sided (can stored on both sides of the platter)?
1
5
10