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CS439: Principles of Computer Systems

Homework 9

(Source: Alison NOrman.)

Due: 11:59 PM Monday, April 8, 2013

Homeworks will be submitted electronically. Please refer to the homework turnin instructions.

  1. Is it fundamentally necessary to store on disk the information about the unallocated disk sectors? Explain why.

  2. Pooh Software Ltd. is selling a file system that uses a UNIX-like file system with multi-level indexing. For more reliability, the inode array is actually replicated on the disk in two different places. The intent is that if one or a group of sectors that are storing either replica of the array become bad, the system can always recover from the replica. Discuss the effect of having this replicated data structure on performance.

  3. True or False. A virtual memory system that uses paging is vulnerable to external fragmentation.

  4. Some file allocation schemes limit the size of the file whether or not there is enough space for a larger file. Which ones and why?
    1. Linked
    2. File Allocation Table
    3. Multi-level index
    4. Contiguous
  5. Which file allocation scheme that we studied is most similar to paging? segmentation?