Data Technology and Future Emergence
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What is the primary function of the NameNode in HDFS?

  • Store data blocks of files
  • Maintain the file system namespace and manage access permissions (correct)
  • Handle backup and restore operations
  • Execute data processing tasks across nodes

    • How does HDFS handle large files?

  • It stores them as single uncompressed files on the NameNode
  • It automatically replicates the entire file on all nodes
  • It compresses and encrypts them for storage
  • It divides them into blocks and stores them on DataNodes (correct)

    • What is the role of DataNodes in HDFS?

  • Store the data blocks of files (correct)
  • Manage client access to files
  • Execute data processing tasks
  • Store metadata about file blocks

    • What is a characteristic of the DataNodes in HDFS?

    <p>They are resilient but not smart</p> Signup and view all the answers

    How many blocks will HDFS create for a file of size 612 Mb with a block size of 128 Mb?

    <p>Four blocks of 128 Mb and one block of 100 Mb</p> Signup and view all the answers

    What does the replication mechanism in HDFS achieve?

    <p>Increases data availability by duplicating blocks across multiple nodes</p> Signup and view all the answers

    What does the NameNode use to keep track of the data nodes in the cluster?

    <p>Rack ID</p> Signup and view all the answers

    Which statement correctly describes the master-slave architecture of HDFS?

    <p>There is only one master node that manages multiple slave nodes for data storage.</p> Signup and view all the answers

    What does NoSQL stand for?

    <p>Not Only SQL</p> Signup and view all the answers

    Which of the following is a key benefit of sharding in NoSQL databases?

    <p>Improved manageability of datasets</p> Signup and view all the answers

    What is a common problem associated with master-slave replication?

    <p>Read inconsistency</p> Signup and view all the answers

    In peer-to-peer replication, how do nodes interact?

    <p>All nodes are equal and can handle reads and writes.</p> Signup and view all the answers

    How does NoSQL database structure its schema compared to SQL databases?

    <p>It has a flexible schema.</p> Signup and view all the answers

    What is one of the two methods used in NoSQL replication?

    <p>Master-Slave replication</p> Signup and view all the answers

    One advantage of NoSQL databases is that they are good with sparse table matrices. What does this mean?

    <p>They can efficiently handle incomplete data entries.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of NoSQL databases?

    <p>Optimized for join operations</p> Signup and view all the answers

    What is the primary purpose of transaction logs in HDFS?

    <p>To keep track of every operation and assist in auditing</p> Signup and view all the answers

    How does HDFS ensure data integrity during file operations?

    <p>By using checksums to verify file contents</p> Signup and view all the answers

    What is the default replication factor for HDFS?

    <p>3</p> Signup and view all the answers

    What benefit does rack awareness provide in HDFS?

    <p>Minimizes latency by locating data blocks strategically</p> Signup and view all the answers

    Which feature in Hadoop 2.0 addresses the Single Point Of Failure (SPOF) issue?

    <p>Multiple NameNodes support</p> Signup and view all the answers

    What role do checksum files play in HDFS?

    <p>They are used to prevent tampering through validation</p> Signup and view all the answers

    How does HDFS ensure fault-tolerance during data replication?

    <p>By distributing replicas across different racks and nodes</p> Signup and view all the answers

    What does HDFS use to enhance network bandwidth during data operations?

    <p>Closet replication strategy</p> Signup and view all the answers

    What is a characteristic of on-disk storage?

    <p>Relies on low-cost hard-disk drives for long-term storage.</p> Signup and view all the answers

    Which of the following is a feature of a distributed file system?

    <p>Provides redundancy and high availability through data replication.</p> Signup and view all the answers

    What is a major limitation of relational DBMS?

    <p>Requires complex manual sharding for data processing.</p> Signup and view all the answers

    Which property of ACID ensures that once a transaction is completed, results remain permanent?

    <p>Durability</p> Signup and view all the answers

    What best describes schema-based storage in relation to data types?

    <p>Ideal for applications requiring strict data consistency.</p> Signup and view all the answers

    Which statement about non-relational databases is true?

    <p>Are better suited for unstructured and semi-structured data.</p> Signup and view all the answers

    What concurrency control is primarily used by relational DBMS?

    <p>Pessimistic concurrency controls.</p> Signup and view all the answers

    Which is a benefit of using distributed file systems over traditional database systems?

    <p>Out-of-the-box support for redundancy and fault tolerance.</p> Signup and view all the answers

    What is the primary reason HDFS is well-suited for big data analysis?

    <p>Data is written once and read many times thereafter.</p> Signup and view all the answers

    How does HDFS ensure data reliability?

    <p>Through the replication of data blocks across multiple locations.</p> Signup and view all the answers

    What is the default block size for files in HDFS?

    <p>128 MB</p> Signup and view all the answers

    What is the function of the NameNode in an HDFS?

    <p>To manage access to files and data nodes.</p> Signup and view all the answers

    Which of the following best describes horizontal scalability in HDFS?

    <p>The ability to increase capacity by adding more nodes.</p> Signup and view all the answers

    Why was HDFS developed to handle hardware failures?

    <p>To maintain data reliability and integrity during failures.</p> Signup and view all the answers

    What is the advantage of breaking large files into smaller blocks in HDFS?

    <p>It simplifies the process of data replication.</p> Signup and view all the answers

    Which characteristic defines HDFS's ability to work with various data types?

    <p>Compatible with semi-structured, unstructured, and structured data.</p> Signup and view all the answers

    Signup and view all the answers

    Study Notes

    Data Technology and Future Emergence

    • The course is DSC650: Data Technology and Future Emergence.
    • The lecture is titled "Data Storage Technology."
    • The lecturer is Dr. Khairul Anwar Hj. Sedek.

    Lecture Outlines

    • The lecture covers the evolution of data storage, including on-disk storage, distributed file systems, RDBMS, NoSQL databases.
    • It also covers the comparison between SQL and NoSQL databases, and the Hadoop Distributed File System (HDFS).
    • Students will be able to demonstrate an understanding of basic concepts and practices of big data technology.

    Evolution of Data Storage

    • Data storage has evolved significantly from punch cards in the 1800s to cloud storage.
    • Key milestones include floppy disks, flash drives, secure digital (SD) cards, and cloud storage.
    • Cloud storage, invented in the 1960s, became commercially available in 1983.

    Evolution of Data Storage (Specific Technologies)

    • Punch Cards (1837-mid 1980s): Early method of storing data using punched cards.

    • Floppy Disks (1967-mid 1990s): 8-inch, 5-inch, and 3 1/2-inch floppy disks were used commonly.

    • Flash Drives (1999): Small, portable devices for storing data.

    • Secure Digital (SD) Cards (1999): Small cards for storing data, including SD, miniSD, and microSD cards.

    • Cloud Storage: Invented in the 1960s, but commercially available later.

    • Other historical technologies are noted in the presentation. For example, magnetic tapes, magnetic drums, Williams Tube, Twistor Memory, Bubble Memory, Delay Line Memory, Magnetic Cores, hard disks, CD-ROMs, DVDs, Smart Media, Multimedia cards, Micro drives, xD-Picture Cards, Compact Flash.

    On-Disk Storage

    • On-disk storage uses low-cost hard disk drives for long-term storage.
    • Implementation is via a distributed file system or a database.

    Distributed File Systems (DFS)

    • Support schema-less data storage.
    • Provides out-of-box redundancy and high availability via replication across multiple locations.
    • Offers fast read and write capabilities.
    • Multiple smaller files can be combined into a single file for optimal storage and processing.

    Relational DBMS

    • ACID-compliant: restricted to a single node; does not provide out-of-the-box redundancy and fault tolerance.
    • Less ideal for long-term storage of accumulating data
    • Manually sharded to process data from multiple shards.
    • Schema based – not ideal for semi-/unstructured data.
    • Data checking against schema constraints introduces latency.
    • Uses record locks for consistent transactions.

    NoSQL Database

    • NoSQL stands for "Not Only SQL"
    • NoSQL databases are non-relational, highly scalable, and fault-tolerant.
    • Designed for semi-/unstructured data.
    • Provide API-based query interface to be called from within applications.

    NoSQL Database: Sharding

    • Sharding is the process of horizontally partitioning large datasets into smaller, more manageable shards.
    • Shards are distributed across multiple nodes (servers).
    • Each shard contains only a portion of the data
    • Each node is responsible for managing only the relevant data.
    • All shards share the same schema.
    • Together they represent the complete dataset.

    NoSQL Database: Replication

    • Replication stores multiple copies (replicas) of a dataset on multiple nodes.
    • Provides scalability and high availability.
    • Data redundancy (using multiple copies) helps with fault tolerance.
    • Two replication methods: master-slave, and peer-to-peer.

    NoSQL Database: Master-Slave Replication

    • Nodes are arranged in a master-slave configuration.
    • Data is initially written to the master node.
    • The master node replicates data on multiple slave nodes.
    • External write requests are handled by the master node.
    • Read requests can be fulfilled from any slave node.
    • Potential problem: read inconsistency.
    • Solution: voting system

    NoSQL Database: Peer-to-Peer Replication

    • All nodes operate at the same level as peers.
    • Each node has equal capabilities for read and write operations.
    • Each write is copied to all peers.
    • Potential problem: simultaneous update inconsistencies.

    NoSQL vs SQL

    • Comparison of characteristics including: row-oriented/column-oriented, fixed schema/flexible schema, optimizing for sparse matrices, join operations, integration, sharding, and data types supported.

    Hadoop Distributed File System (HDFS)

    • HDFS is a versatile, resilient, clustered approach for managing files in big data environments.
    • It is not the final destination for files but a data service.
    • It handles high data volumes and velocity.
    • Data is written once and read many times.
    • It is an excellent choice for big data analysis.

    Hadoop Distributed File System

    • Motivations for developing HDFS: Hardware failure, need for streaming access to large datasets, data coherency issues, cheaper computation, heterogeneous platforms.
    • HDFS breaks large files into smaller blocks, typically 128 MB.
    • Blocks are replicated for reliability across multiple nodes.
    • Understands rack locality, enabling computational efficiency in data migration.
    • Client talks to both NameNode and DataNodes, with data access directly from DataNodes.
    • Throughput scales nearly linearly with the number of nodes.

    Data Block in Hadoop HDFS

    • HDFS internally splits files into block-sized chunks.
    • Block size defaults to 128 MB, but configurable.

    HDFS Architecture

    • HDFS follows a master-slave architecture with a single NameNode and multiple DataNodes.
    • The NameNode manages the file system namespace and provides access permissions to clients.
    • Blocks are stored on DataNodes.

    HDFS NameNodes

    • The NameNode acts as the central hub for the HDFS system.
    • It manages the file system namespace.
    • It manages access to data blocks for clients (read, write, create, delete, replication).

    HDFS DataNodes

    • DataNodes store blocks of files.
    • They are resilient within the HDFS cluster
    • Replication mechanism is designed for optimal efficiency when nodes are in the same rack
    • Uses "rack ID" to track data nodes.

    HDFS Key Features

    • Includes features like: rack awareness, high availability, replication management, and data read and write operations.

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    Related Documents

    Lecture 3 - Data Storage Technology PDF

    Description

    Explore the fascinating evolution of data storage technology from its origins to modern cloud solutions. This quiz covers key concepts, including on-disk storage, RDBMS, NoSQL databases, and the Hadoop Distributed File System (HDFS). Test your understanding of big data technology and its applications.

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