[SCENARIO-BASED ] Apache Flume Interview Questions and Answers
Apache-Flume-Interview-Questions-and-Answers

[SCENARIO-BASED ] Apache Flume Interview Questions and Answers

Last updated on 10th Nov 2021, Blog, Interview Questions

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We will discuss in this article, “Top Flume Interview Questions and answers” we are providing Advanced Apache Flume Interview Questions that will help you in cracking your interview as well as to acquire a dream career as an Apache Flume Developer. If we talk about the current world, there are a lot of opportunities in Flume Development in many reputed companies across the world. On the basis of research, we can say Flume has a market share of about 70.37%. Hence, we have a huge opportunity to move ahead in our career in Apache Flume Development. However, to go for Flume jobs it is important to learn Apache Flume in deep. So, if you’re looking for Flume Interview Questions & Answers for Experienced or Freshers, you are at the right place.


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    1. What is Apache Flume?

    Ans:

      As we know, whereas it involves efficiency and dependably collect, mixture and transfer large amounts from one or additional supply’s to a centralized data source we tend to use Apache Flume. However, it will ingest any reasonable knowledge together with log knowledge, event data, network knowledge, social-media generated knowledge, email messages, message queues etc since knowledge sources are unit customizable in Flume.

    Basic Features of flume

    2. What are the Basic Features of flume?

    Ans:

    • A data collection service for Hadoop: Using Flume, we can get the data from multiple servers immediately into Hadoop.
    • For distributed systems: Along with the log files, Flume is also used to import huge volumes of event data produced by social networking sites like Facebook and Twitter, and e-commerce websites like Amazon and Flipkart.
    • Open source: It is open-source software. It doesn’t require any license key for its activation. Scalable: Flume can be scaled horizontally.

    3. What are some applications of Flume?

    Ans:

      Assume a web application wants to analyze the customer behaviors about current activity. So this is where Flume comes in handy. It extracts data and moves the data to Hadoop for analysis. Flume is used to move the log data generated by application servers into HDFS at a higher speed.

    4. What is an Agent?

    Ans:

      A process that hosts flume components such as sources, channels, and sinks, and thus has the ability to receive, store and forward events to their destination.

    5. What is a channel?

    Ans:

      It stores events, events are delivered to the channel via sources operating within the agent. An event stays in the channel until a sink removes it for further transport.

    6. Does Apache Flume provide support for third-party plug-ins?

    Ans:

      Most of the data analysts using Apache Flume have plug-in based architecture as it can load data from external sources and transfer it to external destinations.

    7. What’s FlumeNG?

    Ans:

      FlumeNG is nothing but a period loader for streaming your knowledge into Hadoop. Basically, it stores knowledge in HDFS and HBase. Thus, if we wish to start with FlumeNG, it improves on the first flume.

    8. How do you handle agent failures?

    Ans:

      If the Flume agent goes down then all flows hosted on that agent are aborted. Once the agent is restarted then the flow will resume. If the channel is set up as an in-memory channel then all events that are stored in the channels when the agent went down are lost. But channels set up as a file or other stable channels will continue to process events where it left off.

    9. Can Flume distribute data to multiple destinations?

    Ans:

      Yes. It supports multiplexing flow. The event flows from one source to multiple channels and multiple destinations, It is achieved by defining a flow multiplexer.

    10. What is Flume?

    Ans:

      Flume is a reliable distributed service for the collection and aggregation of large amounts of streaming data into HDFS. Most of the Big data analysts use Apache Flume to push data from different sources like Twitter, Facebook, & LinkedIn into Hadoop, Strom, Solr, Kafka & Spark.

    11. Why are we using Flume?

    Ans:

      Most often Hadoop developers use this tool to get log data from social media sites. It’s developed by Cloudera for aggregating and moving a very large amount of data. The primary use is to gather log files from different sources and asynchronously persists in the Hadoop cluster.

    12. What is Flume Agent?

    Ans:

      A Flume agent is a JVM process that holds the Flume core components (Source, Channel, Sink. through which events flow from an external source like web-servers to the destination like HDFS. An agent is the heart of the Apache Flume.

    13. What are Flume Core components?

    Ans:

      Source, Channels, and Sink are core components in Apache Flume.

      When the Flume source receives an event from external sources, it stores the event in one or multiple channels.

      Flume channel is temporarily stored & keeps the event until it’s consumed by the Flume sink. It acts as a Flume repository.

      Flume Sink removes the event from the channel and puts it into an external repository like HDFS or Move to the next Flume agent.

    Flume Core components

    14. Can Flume provide 100% reliability to the data flow?

    Ans:

      Yes, it provides end-to-end reliability of the flow. By default, Flume uses a transactional approach in the data flow. Sources and sinks encapsulated in a transactional repository provided by the channels. These channels were responsible to pass reliably from end to end in the flow. So it provides 100% reliability to the data flow.

    15. Can you explain about configuration files?

    Ans:

      The agent configuration is stored in the local configuration file. It comprises each agent’s source, sinks, and channel information. Each core component such as source, sink, and a channel has properties such as name, type and set of properties.

      For example, Avro source needs hostname, the port number to receive data from an external client. The memory channel should have a maximum queue size in the form of capacity. The sink should have File System URI, Path to create files, frequency of file rotation and more configurations.

    16. What are the complicated steps in Flume configuration?

    Ans:

      Flume can process streaming data, so if started once, there is no stop/end to the process. Asynchronously it can flow data from source to HDFS via Agent. First of all, agents should know individual components of how they are connected to load data. So the configuration is the trigger to load streaming data. For example, consumer key, Consumer Secret, Access Token and access token secret are key factors to download data from Twitter.

    17. What are the important steps in the configuration?

    Ans:

      The configuration file is the heart of the Apache Flume’s agent.

      1. Every Source must have at least one channel.

      2. Every Sink must have only one channel.

      3. Every Component must have a specific type.

    18. Can you explain Consolidation in Flume?

    Ans:

      The beauty of Flume is Consolidation; it collects data from different sources even it’s different Flume Agents. Flume source can collect all data flow from different sources and flows through channel and sink. Finally, send this data to HDFS or target destination.

    19. Can Flume distribute data to multiple destinations?

    Ans:

      Yes, it supports multiplexing flow. The event flows from one source to multiple channels and multiple destinations. It’s achieved by defining a flow multiplexer. In the above example, data flows and is replicated to HDFS and another sink to destination and another destination is input to another agent.

    20. An Agent communicates with other Agents?

    Ans:

      No, each agent runs independently. Flume can easily scale horizontally. As a result, there is no single point of failure.

    21. What are interceptors?

    Ans:

      It’s one of the most frequently asked Flume interview questions. Interceptors are used to filter the events between source and channel, channel and sink. These channels can filter unnecessary or targeted log files. Depending on requirements you can use a number of interceptors.

    22. What are Channel selectors?

    Ans:

      Channel selectors control and separate the events and allocate them to a particular channel. There are the default/ replicated channel selectors. Replicated channel selectors can replicate the data in multiple/all channels.

      Multiplexing channel selectors used to separate and aggregate the data based on the event’s header information. It means based on Sink’s destination, the event aggregate into the particular sink.

      Leg Example : One sink connected with Hadoop, another with S3 another with Hbase, at that time, Multiplexing channel selectors can separate the events and flow to the particular sink.

    23. What are sink processors?

    Ans:

      Sink processors is a mechanism by which you can create a fail-over task and load balancing.

    24. Which is the reliable channel in Flume to ensure that there is no data loss?

    Ans:

      FILE Channel is the most reliable channel among the 3 channels JDBC, FILE and MEMORY.

    25. How can Flume be used with HBase?

    Ans:

      Apache Flume can be used with HBase using one of the two HBase sinks –

    • HBaseSink (org.apache.flume.sink.hbase.HBaseSink) supports secure HBase clusters and also the novel HBase IPC that was introduced in the version HBase 0.96.
    • AsyncHBaseSink (org.apache.flume.sink.hbase.AsyncHBaseSink) has better performance than HBase sink as it can easily make non-blocking calls to HBase.
    Flume be used with HBase

    26. Is it possible to leverage real-time analysis on the big data collected by Flume directly? If yes, then explain how?

    Ans:

      Data from Flume can be extracted, transformed and loaded in real-time into Apache Solr servers using MorphlineSolrSink.

    27. Explain the different channel types in Flume. Which channel type is faster?

    Ans:

      The 3 different built-in channel types available in Flume are :

    • MEMORY Channel – Events are read from the source into memory and passed to the sink.
    • JDBC Channel – JDBC Channel stores the events in an embedded Derby database.
    • FILE Channel –File Channel writes the contents to a file on the file system after reading the event from a source. The file is deleted only after the contents are successfully delivered to the sink.
    • MEMORY Channel is the fastest channel among the three however has the risk of data loss. The channel that you choose completely depends on the nature of the big data application and the value of each event.

    28. Explain about the replication and multiplexing selectors in Flume.

    Ans:

      Channel Selectors are used to handling multiple channels. Based on the Flume header value, an event can be written just to a single channel or to multiple channels. If a channel selector is not specified to the source, then by default it is the Replicating selector. Using the replicating selector, the same event is written to all the channels in the source’s channels list. The multiplexing channel selector is used when the application has to send different events to different channels.

    29. Does Apache Flume provide support for third-party plug-ins?

    Ans:

      Most of the data analysts use Apache Flume has a plug-in based architecture as it can load data from external sources and transfer it to external destinations.

    30. Differentiate between FileSink and FileRollSink

    Ans:

      The major difference between HDFS FileSink and FileRollSink is that HDFS File Sink writes the events into the Hadoop Distributed File System (HDFS. whereas File Roll Sink stores the events into the local file system.

    31. Can Flume distribute data to multiple destinations?

    Ans:

      Yes. It supports multiplexing flow. The event flows from one source to multiple channels and multiple destinations, it is achieved by defining a flow multiplexer.

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    32. How multi-hop agents can be set up in Flume?

    Ans:

      The Avro RPC Bridge mechanism is used to set up the Multi-hop agent in Apache Flume.

    33. What is FlumeNG?

    Ans:

      A real-time loader for streaming your data into Hadoop. It stores data in HDFS and HBase. You’ll want to get started with FlumeNG, which improves on the original flume.

    FlumeNG

    34. An Agent communicates with other Agents?

    Ans:

      NO each agent runs independently. Flume can easily horizontally. As a result, there is no single point of failure.

    35. What are the Data extraction tools in Hadoop?

    Ans:

      Sqoop can be used to transfer data between RDBMS and HDFS. Flume can be used to extract the streaming data from social media, weblog, etc. and store it on HDFS.

    36. Tell me any two features of Flume?

    Ans:

      Fume collects data efficiently, aggregates and moves large amounts of log data from many different sources to centralized data stores.

      Flume is not restricted to log data aggregation and it can transport a massive quantity of event data including but not limited to network traffic data, social-media generated data, email messages and pretty much any data storage.

    37. Which Is The Reliable Channel In Flume To Ensure That There Is No Data Loss?

    Ans:

      FILE Channel is the most reliable channel among the 3 channels JDBC, FILE and MEMORY.

    38. How Can Flume Be Used With Hbase?

    Ans:

      Apache Flume can be used with HBase using one of the two HBase links :

    • HBaseSink (org.apache.flume.sink.hbase.HBaseSink) supports secure HBase clusters and also the novel HBase IPC that was introduced in the version HBase 0.96.
    • AsyncHBaseSink (org.apache.flume.sink.hbase.AsyncHBaseSink) has better performance than HBase sink as it can easily make non-blocking calls to HBase.

    • Working of the HBaseSink :

      In HBaseSink, a Flume Event is converted into HBase Increments or Puts. Serializer implements the HBaseEventSerializer which is then instantiated when the sink starts. For every event, sink calls the initialize method in the serializer which then translates the Flume Event into HBase increments and puts to be sent to the HBase cluster.

      Working of the AsyncHBaseSink :

      AsyncHBaseSink implements the AsyncHBaseEventSerializer. The initialize method is called only once by the sink when it starts. Sink invokes the setEvent method and then makes calls to the getIncrements and getActions methods just similar to HBase sink. When the sink stops, the cleanUp method is called by the serializer.

    39. Is It Possible To Leverage Real Time Analysis On The Big Data Collected By Flume Directly? If Yes, Then Explain How?

    Ans:

      Data from Flume can be extracted, transformed and loaded in real-time into Apache Solr servers usingMorphlineSolrSink.

    40. Where is Agent configuration stored in flume?

    Ans:

      Flume agent configuration is stored in a local configuration file. This is a text file that follows the Java properties file format. Configurations for one or more agents can be specified in the same configuration file.

    Agent configuration stored in flume

    41. Explain About The Replication And Multiplexing Selectors In Flume?

    Ans:

      Channel Selectors are used to handle multiple channels. Based on the Flume header value, an event can be written just to a single channel or to multiple channels. If a channel selector is not specified to the source then by default it is the Replicating selector. Using the replicating selector, the same event is written to all the channels in the source’s channels list. Multiplexing channel selector is used when the application has to send different events to different channels.

    42. Differentiate Between Filesink And Filerollsink?

    Ans:

      The major difference between HDFS FileSink and FileRollSink is that HDFS File Sink writes the events into the Hadoop Distributed File System (HDFS. whereas File Roll Sink stores the events into the local file system.

    43. Why Are We Using Flume?

    Ans:

      Most often Hadoop developers use this too to get data from social media sites. It is developed by Cloudera for aggregating and moving very large amounts of data. The primary use is to gather log files from different sources and asynchronously persist in the hadoop cluster.

    44. Explain What Are The Tools Used In Big Data?

    Ans:

      Tools used in Big Data includes :

    • Hadoop
    • Hive
    • Pig
    • Flume
    • Mahout
    • Sqoop

    45. What Are The Data Extraction Tools In Hadoop?

    Ans:

      Sqoop can be used to transfer data between RDBMS and HDFS. Flume can be used to extract the streaming data from social media, web log etc and store it on HDFS.

    46. Does Flume Provide 100% Reliability To The Data Flow?

    Ans:

      Yes, Apache Flume provides end to end reliability because of its transactional approach in data flow.

    47. Why Flume.?

    Ans:

      Flume is not limited to collect logs from distributed systems, but it is capable of performing other use cases such as :

    • Collecting readings from an array of sensors.
    • Collecting impressions from custom apps for an ad network.
    • Collecting readings from network devices in order to monitor their performance.
    • Flume is targeted to preserve the reliability, scalability, manageability and extensibility while it serves maximum number of clients with higher QoS

    48. What Is a Flume Event?

    Ans:

      A unit of data with a set of string attributes called Flume event. The external source, like a web-server, sends events to the source. Internally Flume has inbuilt functionality to understand the source format.

      Each log file is consider as an event. Each event has header and value sectors, which has header information and appropriate value that is assigned to a particular header.

    Flume Event

    49. Can You Explain About Configuration Files?

    Ans:

      The agent configuration is stored in the local configuration file. it comprises each agent’s source, sink and channel information.

    50. What Are The Similarities And Differences Between Apache Flume And Apache Kafka?

    Ans:

      Flume pushes messages to their destination via its Sinks.With Kafka you need to consume messages from Kafka Broker using a Kafka Consumer API.

    51. Explain Reliability And Failure Handling In Apache Flume?

    Ans:

      Flume NG uses channel-based transactions to guarantee reliable message delivery. When a message moves from one agent to another, two transactions are started, one on the agent that delivers the event and the other on the agent that receives the event. In order for the sending agent to commit it’s transaction, it must receive a success indication from the receiving agent.

      The receiving agent only returns a success indication if it’s own transaction commits properly first. This ensures guaranteed delivery semantics between the hops that the flow makes. Figure below shows a sequence diagram that illustrates the relative scope and duration of the transactions operating within the two interacting agents.

    52. Differentiate between FileSink and FileRollSink

    Ans:

      The major difference between HDFS FileSink and FileRollSink is that HDFS File Sink writes the events into the Hadoop Distributed File System (HDFS) whereas File Roll Sink stores the events into the local file system.

    53. Will flume give 100 percent responsibility to the information flow?

    Ans:

      Flume usually offers the end-to-end responsibleness of the flow. Also, it uses a transactional approach to the information flow, by default.

      In addition, supply and sink encapsulate in a very transactional repository provides the channels. Moreover, to pass dependably from finish to finish flow these channels are accountable. Hence, it offers 100 percent responsibleness to the information flow.

    54. What’s an associate Agent?

    Ans:

      In Apache Flume, associate freelance daemon method (JVM) is what we tend to decide associate agent. At first, it receives events from purchasers or different agents. Afterwards, it forwards it to its next destination that’s sink or agent. Note that, it’s attainable that Flume will have quite one agent. Also, refer to the below image to grasp the Flume Agent.

    55. Is it attainable to leverage period analysis of the large knowledge collected by Flume directly? If affirmative, then make a case for how?

    Ans:

      By victimising MorphlineSolrSink we will extract, rework and cargo knowledge from Flume in period into Apache Solr servers.

    56. How do you check the integrity of file channels?

    Ans:

      Fluid platform provides a File Channel Integrity tool which verifies the integrity of individual events in the File channel and removes corrupted events.

    the integrity of file channels

    57. What do you mean by Apache Web Server?

    Ans:

      Apache web server is the HTTP web server that is open source, and it is used for hosting the website.

    58. How to check the Apache version?

    Ans:

      You can use the command httpd -v.

    59. Does apache run on which users and how to check the location of the config file?

    Ans:

      Apache runs on the nobody user, and the config file’s location is /etc/httpd/conf/httpd.conf.

    60. What is the port of HTTP and https of Apache?

    Ans:

      The port of HTTP is 80, and https is 443 in Apache.

    61. How will you install the Apache server on Linux Machine?

    Ans:

      This is the common Apache Interview Question asked in an interview. We can give the following command for Centos and Debian, respectively :

      Centos : yum install httpd

      Debian : apt-get install apache2.

    62. Where are the configuration directories of the Apache web server?

    Ans:

      You can use the following command :

      cd /etc/HTTP and type ls -l

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    63. Can we install two apache web servers on one Single machine?

    Ans:

      The answer is Yes, we can install the two apache web server on one machine, but we have to define two different ports on that.

    64. What DocumentRoot refers to in Apache?

    Ans:

      It means the web file location, which is stored on the server.

      For Example : /var/www.

    DocumentRoot refers to in Apache

    65. What do you mean by the Alias Directive?

    Ans:

      The alias directive is responsible for mapping resources in the file system.

    66. What do you mean by Directory Index?

    Ans:

      It is the first file that the apache server looks for when any request comes from a domain.

    67. What do you mean by the log files of the Apache web server?

    Ans:

      We can access the log files of Apache server from the below location : /var/log/httpd/access_log and error log from /var/log/httpd/error_log.

    68. What do you mean by a virtual host is Apache?

    Ans:

      The virtual host section contains the information regarding your Website name, Directory Index, Server Admin and Email and information of error logs.

    69. Explain the difference between location and Directory.

    Ans:

      For setting the element related to the URL, we use:: Location.

      It refers to the location of the files system of the server:: Directory.

    70. What do you mean by Apache Virtual Hosting?

    Ans:

      Hosting multiple websites on a single web server is known as Apache Virtual Hosting. There are two types of virtual hosting: Name-Based Virtual Hosting and IP Based Virtual Hosting.

    71. What do you mean by MPM in Apache?

    Ans:

      In Apache, MPM stands for Multi-Processing Modules.

    72. What do you mean by mod_perl and mod_php?

    Ans:

      mod_perl is used for enhancing the performance of Perl scripts.

      mod_php is used for enhancing the performance of PHP scripts.

    73. What do you mean by Mod_evasive?

    Ans:

      It is the module that helps the webserver to prevent web attacks

      Example : DDOS.

    74. What do you mean by Loglevel debug in httpd.conf file?

    Ans:

      With Loglevel debugs help, we can find more information regarding the error logs, which is used to solve the problem.

    75. How to start and stop the Apache Web server?

    Ans:

      This is the most popular Apache Interview Question asked in an interview. Inside the Apache instance location, there is a bin folder, and inside the bin folder, there will be an executable script. We can use the below command in the bin folder via terminal :

      For start : ./apachectl start

      For stop : ./apachectl stop

    76. What is the command to change the default Listen port?

    Ans:

      We can give a command like this: Listen 9.126.8.139:8000. This command will change the default listen port and make the listening port 8000.

    77. What is the flume config file in flume?

    Ans:

      Flume agent configuration file flume.conf resembles a Java property file format with hierarchical property settings. Here the filename flume.conf is not fixed, and we can provide any name to it and need to use the same name when starting agent with flume-ng command.

    78. What is the log level of Apache?

    Ans:

      The log level is: debug, info, warn, notice, crit, alarm, emerg, error.

    79. How will you kill the Apache process?

    Ans:

      We can use the below command :

      • Kill $PID NUMBER

    80. What do you mean by these error codes 200, 403 and 503?

    Ans:

      200 – The server is ok.

      403 – Server is trying to access the restricted file.

      503 –Server is busy.

    81. How will you check the httpd.conf consistency?

    Ans:

      By giving the below command :

      • httpd -t

    82. How will you enable the PHP scripts on the server?

    Ans:

      We have to follow the steps :

      First, install mod_php.

      Second run the command : AddHandler application/x-httpd-PHP .phtml .php

    83. Does flume have plugin-based architecture?

    Ans:

      Answer : Yes, Flume has 100% plugin-based architecture, it can load and ship data from external sources to external destinations which are separate from Flume. So most of the big data analysis uses this tool for streaming data.

    plugin-based architecture

    84. What is a flume source?

    Ans:

      A Flume source is the component of Flume Agent which consumes data (events. from data generators like a web server and delivers it to one or more channels. The data generator sends data (events. to Flume in a format recognized by the target Flume source.

    85. What is the use of flume in big data?

    Ans:

      Flume is a reliable distributed service for the collection and aggregation of large amounts of streaming data into HDFS. Most of the Big data analysts use Apache Flume to push data from different sources like Twitter, Facebook, & LinkedIn into Hadoop, Strom, Solr, Kafka & Spark.

    86. What is an external source of flume?

    Ans:

      The external source sends events to Flume in a format that is recognized by the target Flume source. For example, an Avro Flume source can be used to receive Avro events from Avro clients or other Flume agents in the flow that send events from an Avro sink.

    87. What are the components of a flume agent?

    Ans:

      As shown in the diagram a Flume Agent contains three main components namely, source, channel, and sink. A source is the component of an Agent which receives data from the data generators and transfers it to one or more channels in the form of Flume events.

    88. What is the use of flume in HDFS?

    Ans:

      Flume is a framework which is used to move log data into HDFS. Generally events and log data are generated by the log servers and these servers have Flume agents running on them. These agents receive the data from the data generators. The data in these agents will be collected by an intermediate node known as Collector.

    89. How do I view the data sent by flume to HDFS?

    Ans:

      In the Hue File Browser, open the /user/cloudera/flume/events directory. There will be a file named FlumeData with a serial number as the file extension. Click the file name link to view the data sent by Flume to HDFS.

    90. How to send the streaming data to HDFS?

    Ans:

      Tools available to send the streaming data to HDFS. To transfer the streaming data (log files, events etc..,. from various sources to HDFS, there are following tools available: A very popular tool we use is Scribe, to aggregate and stream the log data.

    91. What is flume in Hadoop HDFS?

    Ans:

      It is another top-level project from the Apache Software Foundation that is developed to provide continuous data injection in Hadoop HDFS. The data can be any kind of data, but Flume is mainly well-suited to handle log data, such as the log data from web servers.

    92. How to check if sequence data has been loaded to HDFS?

    Ans:

      To check if the sequence data has been loaded to HDFS, access the URL: http://master:50070 The above steps demonstrated the single Agent. The typical use case of Flume is to collect the system logs from many Web servers.

    93. How to implement HDFS sink in flume?

    Ans:

      The HDFS sink requires the file system URI, a path to creating files, etc. All such component attributes must be set in the properties file of the hosting Flume agent. 3. Writing the pieces together The flume agent must know the individual components to load. The agent needs to know how the connectivity of the components constitutes the flow.

    implement HDFS sink in flume

    94. How to send the streaming data to HDFS?

    Ans:

      Tools available to send the streaming data to HDFS. To transfer the streaming data (log files, events etc…) from various sources to HDFS, there are following tools available: A very popular tool we use is Scribe, to aggregate and stream the log data.

    95. What is the difference between HDFS and streaming?

    Ans:

      Streaming just implies that it can offer you a constant bitrate above a certain threshold when transferring the data, as opposed to having the data come in in bursts or waves. If HDFS is laid out for streaming, it will probably still support seek, with a bit of overhead it requires to cache the data for a constant stream.

    96. Does HDFS support seek?

    Ans:

      If HDFS is laid out for streaming, it will probably still support seek, with a bit of overhead it requires to cache the data for a constant stream. Of course, depending on system and network load, your seeks might take a bit longer. HDFS stores data in large blocks — like 64 MB.

    97. How to send data from agent_demo to HDFS?

    Ans:

      The agent_demo is reading data from an external Avro client. It is then sending data to the HDFS through a memory channel. The config file weblogs.config would look like: This will make the data flow from avro_src_1 to hdfs_cluster_1 through the memory channel mem_channel_1.

    98. How is data streamed off the hard drive?

    Ans:

      The data is “streamed” off the hard drive by maintaining the maximum I/O rate that the drive can sustain for these large blocks of data. HDFS is built around the idea that the most efficient data processing pattern is a write-once, read-many-times pattern.

    99. What is the use of a sink in a flume?

    Ans:

      It is used for storing data into a centralized store such as HDFS, HBase, etc. Sink consumes events from the Flume channel and pushes them on to the central repository. In simple words, the component that removes events from a Flume agent and writes it to another flume agent or some other system or a data store is called a sink.

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    100. How do I view the data sent by flume to HDFS?

    Ans:

      In the Hue File Browser, open the /user/cloudera/flume/events directory. There will be a file named FlumeData with a serial number as the file extension. Click the file name link to view the data sent by Flume to HDFS.

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