DSTN-First,Mid-Sem-Regular,2017-2018


Birla Institute of Technology & Science, Pilani
Work-Integrated Learning Programmes Division
First Semester 2017-2018
Mid-Semester Test  (EC-2 Regular)

Course No.                  : IS ZC446/ ES ZC446/ CSI ZC446  
Course Title                 : DATA STORAGE TECHNOLOGY & NETWORKS  
Nature of Exam           : Closed Book
Weightage                    : 35%
Duration                      : 2 Hours 
Date of Exam              : 23/09/2017    (FN)
Note:
1.       Please follow all the Instructions to Candidates given on the cover page of the answer book.
2.       All parts of a question should be answered consecutively. Each answer should start from a fresh page. 
3.       Assumptions made if any, should be stated clearly at the beginning of your answer.

Q.1.        For the following  question write in brief.
(a)             Give  one example  which is leading to large data explosion .
(b)             write in brief about write amplification in case of SSD.
(c)             Write in brief about garbage collection in case od NAND flace based device
(d)            Give example of structured , semi structured and unstructured data
(e)             Write  in brief about temporal locality of reference                                       [5 X 1 = 5]

Q.2.        For the following  question write in brief.
(a)             What are the three design requirements which storage designer must take into account.
(b)             Compute, network and storage  are considered as three layers . write the functionality of each layer.
(c)             Differentiate between SATA & SAS drive
(d)            List the advantages of zoned data recording?
(e)              Give one advantage & one disadvantage of short  stroking.   [1.5 + 2 + 1.5 + 1.5 + 1.5 = 8]

Q.3.        A disk is rotation at 8000 RPM and Has a  average seek time of 4.2 ms.  The disk has a sector size of 2048 bytes and holds 256 sectors per track.
(a)             compute sustained average  data transfer rate
(b)             Number of I/O operation supported by disk                                                    [1.5 + 1.5 = 3]
           
Q.4.        A operating at 10000 RPM, having  sector size of 2048 bytes, and 160 sectors per track. The average seek time for the drive is 2milliseconds. Estimate the number  of random sector I/Os per second that can be done and the effective average transfer rate for  random-access of a sector?
[2 + 2 = 4]

Q.5.        Given a disk with 200 tracks, where track requests are received in the following order
73, 58, 64, 38, 13, 83, 96, 46, 184.
            The starting position for the arm is track 100. Calculate the number of tracks crossed when the following algorithms are used
(a)             First Come First Serve
(b)             Shortest Seek Time First
(c)             SCAN .                                                                                                                                 [6]

Q.6.        Differentiate between RAID 3  & RAID level 4                                                                               [3]

Q.7.        A computing system uses three level of memory hierarchy. The access time  for level three , level 2 & level 1 is 50 , 30 , 10 microsecond respectively. It is observed that , the level 1 level 2 & level 3 have  95% , 98 % and 100% hit ratio. If data is not found in the level 1 then it is searched in level 2 and if it is not found in level 2 then only it is  accessed from level 3 .  Find the effective access time in microseconds for the system.                                                                    [4]

Q.8.        In RAID level 4 the parity is computed using XOR operation. Why Addition operation for computing the parity cannot be used?                                                                                            [2]
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