Work Sheet 13

  1. Explain the meanings of sector, track and cylinder.
  2. How is the information on the track referenced?
  3. What characteristics determine the disk access speed?
  4. What information is needed for disk I/O?
  5. Do problems 13.1, 13.2, 13.6 and 13.13
  6. (GRE Sample Question?) In the NoNicks OS, the time required by a single file-read operation has 4 nonverlapping components.
    Disk Seek time: 25 ms
    Disk Latency Time: 8 ms
    Disk Transfer Time: 1 ms per 1000 bytes
    OS overhead: 1 ms per 1000 bytes + 10 ms (fixed time) In a version 1 of the system, the file read retrieved blocks of 1000 bytes. In version 2, the file read(along with the underlying layout on the disk) was modified to retrieve blocks of 4000 bytes. The ratio of the time required to read a large file under version2 to the time required to read the same large file under version 1 is about:
    a) 3.5 b) 1.2 c) 3.1 d) 0.35 e) None of the above