Monday, January 9, 2023

BITS-WILP-BDS-Regular 2023-Mid Semester

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Name : MTDSE CLUSTER-MID SEM-1st Sem 2022-2023 EC-2R Jan23
Subject : DSECLZG522 
               BIG DATA SYSTEMS EC 2R
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Q1. Discuss briefly 3 key issues that will impact the performance of a data parallel application and need careful optimization. 

Q2. The CPU of a movie streaming server has L1 cache reference of 0.5 ns and main memory reference of 100 ns. The L1 cache hit during peak hours was found to be 23% of the total memory references.         [Marks: 4]

  1. Calculate the cache hit ratio h.
  2. Find out the average time (Tavg) to access the memory.
  3. If the size of the cache memory is doubled, what will be the impact on h and Tavg.
  4. If there is a total failure of the cache memory, calculate h and Tavg.

Q3. A travel review site stores (user, hotel, review) tuples in a data store. E.g. tuple is (“user1”, “hotel ABC”, “<review>”). The data analysis team wants to know which user has written the most reviews and the hotel that has been reviewed the most. Write MapReduce pseudo-code to answer this question.         [Marks: 4]

Q4. An e-commerce site stores (user, product, rating) tuples for data analysis. E.g. tuple is (“user1”, “product_x”, 3), where rating is from 1-10 with 10 being the best. A user can rate many products and products can be rated by many users. Write MapReduce pseudo-code to find the range (min and max) of ratings received for each product. So each output record contains (<product>, <min rating> to <max rating>).              [Marks: 4]

Q5. Name a system and explain how it utilises the concepts of data and tree parallelism.           [Marks: 3]

Q6. An enterprise application consists of a 2 node active-active application server cluster connected to a 2 node active-passive database (DB) cluster. Both tiers need to be working for the system to be available. Over a long period of time it has been observed that an application server node fails every 100 days and a DB server node fails every 50 days. A passive DB node takes 12 hours to take over from the failed active node. Answer the following questions.            [Marks: 4]

  1. What is the overall MTTF of the 2-tier system ?
  2. Assume only a single failure at any time, either in the App tier or in the DB tier, and an equal probability of an App or a DB node failure. What is your estimate of the availability of the 2-tier system ?

Q7. In the following application scenarios, point out what is most important - consistency or availability, when a system failure results in a network partition in the backend distributed DB. Explain briefly the reason behind your answer.          [Marks: 4]

(a) A limited quantity discount offer on a product for 100 items at an online retail store is almost 98% claimed. (b) An online survey application records inputs from millions of users across the globe.
(c) A travel reservation website is trying to sell rooms at a destination that is seeing very few bookings.
(d) A multi-player game with virtual avatars and users from all across the world needs a set of sequential steps between team members to progress across game milestones.

Q8. Assume that you have a NoSQL database with 3 nodes and a configurable replication factor (RF). R is the number of replicas that participate to return a Read request. W is the number of replicas that need to be updated to acknowledge a Write request. In each of the cases below explain why data is consistent or in-consistent for read requests.               [Marks: 4]

1. RF=1, R=1, W=1.
2. RF=2, R=1, W=Majority/Quorum.
3. RF=3, R=2, W=Majority/Quorum.
4. RF=3, R=Majority/Quorum, W=3.





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