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【技术】数据库-存储层

2022-09-16 06:33:52


structurehierarchyTODOQ08: Disk storage (6 marks)Consider a disk with a block size of 256 bytes, 1,000 tracks per surfac


structure

hierarchy

TODO

Q08: Disk storage (6 marks)

Consider a disk with a block size of 256 bytes, 1,000 tracks per surface, 100 blocks per track,
20 single-sided platters, a rotational speed of 3,600 revolutions per minute, and an average
seek time of 10 msec. Suppose that a file containing 400,000 records of 100 bytes each is to be
stored on such a disk and that no record is allowed to span two blocks.

  1. How many records fit into a block? What is the capacity of this disk?
  2. How many blocks are required to store the entire file?
  3. Assume the data transfer rate is 10 megabytes per second (1 megabyte = 220 bytes), and
    the records are stored sequentially. Compute the average time needed to read a block.

Q09: Buffer management (8 marks)

Consider the following page access sequence:
Time 1: Request Page 5, release it, modified
Time 2: Request Page 8, release it, unmodified
Time 3: Request Page 10, release it, modified
Time 4: Request Page 20
Time 5: Request Page 30, release it, modified
Time 6: Request Page 10, release it, modified
Time 7: Request Page 18, release it, unmodified
Assume the buffer content is as shown below after Time 3. Fill in the buffer content for Times
4-7 under the LRU and MRU policies, respectively. Indicate if a page needs to be written back
to the disk when it is replaced.