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Questions and Answers
What scheduling mechanism is used within each queue in the Capacity Scheduler?
What scheduling mechanism is used within each queue in the Capacity Scheduler?
How does the Capacity Scheduler handle unused capacity among queues?
How does the Capacity Scheduler handle unused capacity among queues?
What is the purpose of limiting the percentage of running tasks per user in the Capacity Scheduler?
What is the purpose of limiting the percentage of running tasks per user in the Capacity Scheduler?
What happens when a queue exceeds its configured wait time without being scheduled?
What happens when a queue exceeds its configured wait time without being scheduled?
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In the Capacity Scheduler, what is the role of guaranteed capacity for each queue?
In the Capacity Scheduler, what is the role of guaranteed capacity for each queue?
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What is the primary role of the TaskTracker in Hadoop 2.0?
What is the primary role of the TaskTracker in Hadoop 2.0?
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Which component is responsible for negotiating resources from the Resource Manager?
Which component is responsible for negotiating resources from the Resource Manager?
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Which of the following best describes a Container in YARN?
Which of the following best describes a Container in YARN?
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What separates the processing engine from resource management in Hadoop 2.0?
What separates the processing engine from resource management in Hadoop 2.0?
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Which service is primarily responsible for enforcing resource scheduling policy in YARN?
Which service is primarily responsible for enforcing resource scheduling policy in YARN?
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In the context of YARN, what is the role of the Applications Manager?
In the context of YARN, what is the role of the Applications Manager?
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What happens when a task process fails in the TaskTracker?
What happens when a task process fails in the TaskTracker?
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Which component in YARN manages user processes on a single machine?
Which component in YARN manages user processes on a single machine?
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What is the primary function of the Map phase in a MapReduce job?
What is the primary function of the Map phase in a MapReduce job?
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Which component is responsible for locating TaskTracker nodes in a MapReduce job execution?
Which component is responsible for locating TaskTracker nodes in a MapReduce job execution?
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What type of messages do TaskTracker nodes send to the JobTracker?
What type of messages do TaskTracker nodes send to the JobTracker?
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In the Reduce phase, what is done with the intermediate data?
In the Reduce phase, what is done with the intermediate data?
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What is the purpose of the optional Combine task in a MapReduce job?
What is the purpose of the optional Combine task in a MapReduce job?
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What is the default scheduling algorithm used by the JobTracker?
What is the default scheduling algorithm used by the JobTracker?
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Which statement about the relationship between TaskTracker instances and DataNode instances is accurate?
Which statement about the relationship between TaskTracker instances and DataNode instances is accurate?
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How does the JobTracker keep updated with the available slots in the TaskTracker nodes?
How does the JobTracker keep updated with the available slots in the TaskTracker nodes?
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What is the primary role of the NameNode in a Hadoop cluster?
What is the primary role of the NameNode in a Hadoop cluster?
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Which of the following components is responsible for executing Map and Reduce tasks in Hadoop?
Which of the following components is responsible for executing Map and Reduce tasks in Hadoop?
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What is a key function of the Secondary NameNode in a Hadoop cluster?
What is a key function of the Secondary NameNode in a Hadoop cluster?
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Which component of the Hadoop ecosystem is primarily used for processing large sets of data in a distributed manner?
Which component of the Hadoop ecosystem is primarily used for processing large sets of data in a distributed manner?
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What does the JobTracker do in a Hadoop cluster?
What does the JobTracker do in a Hadoop cluster?
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In the context of Hadoop, which of the following statements is true regarding DataNodes?
In the context of Hadoop, which of the following statements is true regarding DataNodes?
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What role does YARN play in the Hadoop ecosystem?
What role does YARN play in the Hadoop ecosystem?
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Which of the following components does not belong to the Hadoop ecosystem?
Which of the following components does not belong to the Hadoop ecosystem?
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What is the default scheduler in Hadoop?
What is the default scheduler in Hadoop?
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How does the Fair Scheduler allocate resources to jobs?
How does the Fair Scheduler allocate resources to jobs?
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What happens when there is a single job running in the Fair Scheduler?
What happens when there is a single job running in the Fair Scheduler?
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What is a primary feature of the Capacity Scheduler?
What is a primary feature of the Capacity Scheduler?
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Which statement is true regarding the FIFO Scheduler?
Which statement is true regarding the FIFO Scheduler?
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How does the Fair Scheduler compute which job to schedule next?
How does the Fair Scheduler compute which job to schedule next?
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In the context of Hadoop, what is a 'job pool'?
In the context of Hadoop, what is a 'job pool'?
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What distinguishes the Capacity Scheduler from the Fair Scheduler?
What distinguishes the Capacity Scheduler from the Fair Scheduler?
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Study Notes
Chapter 10: Data Analytics for IoT
- This chapter focuses on data analytics for the Internet of Things (IoT).
- It outlines the Hadoop ecosystem, MapReduce architecture, job execution flow, and schedulers.
- Hadoop is an open-source framework for distributed batch processing of large datasets.
Hadoop Ecosystem
- Apache Hadoop is a framework for distributed batch processing of big data.
- Hadoop MapReduce, HDFS, YARN, HBase, Zookeeper, Pig, Hive, Mahout, Chukwa, Cassandra, Avro, Oozie, Flume, and Sqoop are components of the Hadoop ecosystem.
- These components provide various functionalities for data storage, processing, and analysis.
- The illustration provides a visual representation of these components and their relationships.
Hadoop Cluster Components
- A Hadoop cluster consists of a master node, a backup node, and multiple slave nodes.
- The master node runs the NameNode and JobTracker processes.
- The slave nodes run the DataNode and TaskTracker components.
- The backup node runs the Secondary NameNode process.
- The NameNode maintains the directory structure and tracks file locations across the cluster.
- Clients interact with the NameNode to locate, add, copy, move, or delete files.
- The Secondary NameNode creates checkpoints of the NameSpace.
- The JobTracker distributes tasks to specific nodes in the cluster.
Apache Hadoop Components
- TaskTracker accepts Map, Reduce, and Shuffle tasks from the JobTracker.
- TaskTrackers have slots specifying the number of tasks they can handle.
- DataNode stores data in HDFS.
- Data is replicated across multiple DataNodes to enhance fault tolerance.
- Clients can interact directly with DataNodes after the NameNode provides data location.
- TaskTracker instances are often deployed with DataNode instances for efficient MapReduce operations.
MapReduce
- MapReduce jobs are composed of two phases (Map and Reduce).
- Map phase reads data, partitions it across nodes, and produces intermediate results as key-value pairs.
- Reduce phase aggregates intermediate data with the same key.
- The Combine task, an optional phase, aggregates intermediate data locally before the Reduce phase.
MapReduce Job Execution Workflow
- The client submits a job to the JobTracker.
- JobTracker determines the data location and allocates tasks to TaskTracker instances.
- TaskTrackers periodically send heartbeat signals to the JobTracker.
- TaskTrackers spawn separate processes for different tasks to prevent a failure of one task bringing down the system.
- After task completion, it sends status information to the JobTracker.
MapReduce 2.0 – YARN
- Hadoop 2.0 separated the MapReduce processing engine from resource management.
- YARN effectively operates as an OS for Hadoop.
- It supports varied processing engines such as MapReduce, Apache Tez, and interactive queries (e.g., Apache Storm).
- YARN incorporates Resource Manager and Application Master components.
YARN Components
- Resource Manager (RM) manages global resource allocation.
- Scheduler assigns resources based on policies in the cluster.
- Applications Manager (AsM) manages running applications.
- Application Master (AM) manages the application life cycle.
- Node Manager (NM) manages processes on each node.
- Containers bundle resources (memory, CPU, network) for processes.
Hadoop Schedulers
- Hadoop schedulers are configurable components that support various scheduling algorithms.
- The default scheduler in Hadoop is FIFO (First-In-First-Out).
- Advanced schedulers like Fair Scheduler and Capacity Scheduler are also available, providing workload flexibility and performance constraints, and enabling multitasking.
FIFO Scheduler
- FIFO is the default Hadoop scheduler that works with a queue.
- The jobs are processed in the order they enter the queue.
- Priorities and job sizes are not considered in FIFO.
Fair Scheduler
- The Fair Scheduler distributes resources equally among jobs.
- It ensures each job gets an equal share of resources over time.
- Jobs are placed into pools, with each pool ensuring that a certain capacity is guaranteed.
Capacity Scheduler
- Capacity Scheduler resembles the Fair Scheduler but uses a different philosophy for allocation.
- It creates queues with configurable numbers of Map and Reduce slots.
- It assigns guaranteed capacity to these queues.
- It shares unused capacity among queues to maintain fairness.
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Description
Explore the key concepts of data analytics in the context of the Internet of Things (IoT) through Chapter 10. This chapter covers the Hadoop ecosystem, including MapReduce architecture, job execution flow, and the various components that make up a Hadoop cluster. Understand the roles of master and slave nodes and how they contribute to big data processing.