HW-2 answers Fall 2017.docx

HW-2 answers Fall 2017.docx - NAME ISM 6215 Business...

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NAME - ISM 6215 - Business Database Systems I Spring 2017 HW-2 (Marks 100) (Submit in STZ 351 by October 5 by 3 PM) Answer all questions in the space provided below each question. Questions 1(a) – A fixed disk has 80 cylinders. The tracks in each cylinder are numbered 0-11. The upper surface of the top-most platter and the lower surface of the bottom-most platter are not used for recording data. How many of each of the following are there in the disk: 1. Recording surfaces? 2. Platters? 3. Tracks per recording surface? (3*2 = 6 marks) Question 1(b) – Describe (with definition) different types of times required in processing a book search query on Alibaba.com from your computer in Warrington College of business in Gainesville Florida. Assume that the business logic of search query is stored in the database server and data on all books are stored on hard disk in the data center of Alibaba.com in Beijing China. (14 marks) Answer 1(a) – a. The tracks in each cylinder are numbered 0-11. This means there are 12 recording surfaces on which data can be stored. b. For 12 recording surfaces, with the upper surface of top-most platter and lower surface of bottom-most platter not being the recording surfaces, the disc should have 7 platters . c. Number of tracks per recording surface must be same as the number of cylinders – so there are 80 tracks per recording surface . Answer 1(b) – The following are the different types of time required for processing of book search query. 1
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- Query transfer time over the internet – time required to transfer book search query over the Internet from Gainesville Florida to the database server in Beijing China - Seek time - time required to move the access arm mechanism to the correct cylinder where required book data is stored from whatever cylinder it’s currently positioned. - Head switching time – time required in selecting the read/write head to access the required track of the cylinder. - Rotational delay time – time required for the desired book data on the track to arrive under the read/write head as the disk is spinning. - Transfer time - time required to move the book data from the disk to primary memory of the database server once the previous 3 steps have been completed. - Query result transfer time over the internet - time required to transfer search query result over the internet from the database server in Beijing china to your computer in Gainesville Florida. Question 2(a) – 2
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Note that there could be multiple trips on the same route in a day (For example there are buses from Archer Road to Museum road route every one hour). Also, the scheduled departure time and scheduled arrival time may vary on different days of the week (For example the scheduled departure and arrival times on weekends may differ from the weekdays).
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