Posts (page 99)
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7 min readTo install Hadoop using Ambari setup, first ensure that all the prerequisites are met, such as having a compatible operating system and enough resources allocated to the servers. Then, download and install the Ambari server on a dedicated server.Next, access the Ambari web interface and start the installation wizard. Follow the prompts to specify the cluster name, select the services you want to install (including Hadoop components such as HDFS, YARN, MapReduce, etc.), and configure the cluster.
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6 min readHadoop gives reducers the ability to perform aggregation and analysis on the output of the mappers. Reducers receive the intermediate key-value pairs from the mappers, which they then process and combine based on a common key. This allows for tasks such as counting, summing, averaging, and other types of data manipulation to be performed on large datasets efficiently.
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3 min readTo change file permissions in the Hadoop file system, you can use the command "hadoop fs -chmod" followed by the desired permissions and the file path. The syntax for the command is as follows: hadoop fs -chmod <file_path>. Permissions can be specified using symbolic notation (e.g., u=rwx,g=rw,o=r) or octal notation (e.g., 755). This command will change the permissions of the specified file to the ones you provided.
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4 min readTo increase the Hadoop Filesystem size, you can add more storage nodes to your Hadoop cluster, either by adding more disks to existing nodes or by adding more nodes to the cluster. This will increase the overall storage capacity available to Hadoop.You can also adjust the replication factor of your data in HDFS to consume more storage space. By increasing the replication factor, you can ensure that each block of data is replicated across more nodes, thereby consuming more storage space.
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8 min readTo put a large text file in Hadoop HDFS, you can use the command line interface or the Hadoop File System API. First, make sure you have access to the Hadoop cluster and a text file that you want to upload.To upload the text file using the command line interface, you can use the hadoop fs -put command followed by the path to the file you want to upload and the destination directory in HDFS. For example, hadoop fs -put /path/to/localfile.txt /user/username/hdfsfile.txt.
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6 min readTo remove a disk from a running Hadoop cluster, you first need to safely decommission the data node on the disk you want to remove. This involves marking the node as decommissioned and ensuring that the Hadoop cluster redistributes the blocks that were stored on the disk to other nodes in the cluster. Once the decommission process is completed and all data has been redistributed, you can physically remove the disk from the data node.
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7 min readHadoop follows a memory allocation strategy that is based on the concept of containers. When a job is submitted, Hadoop divides the memory available on each node into equal-sized containers. These containers are then used to run various processes related to the job, such as map tasks, reduce tasks, and other operations.Hadoop also uses a concept called memory management units (MMUs) to allocate memory resources efficiently.
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5 min readTo create a chain mapper in Hadoop, you can use the ChainMapper class provided by the Hadoop API. This class allows you to chain multiple mappers together so that the output of one mapper can be used as the input for the next mapper in the chain.To create a chain mapper, first create a new class that extends the ChainMapper class. Override the map method in this class to define the logic for your mapper.
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3 min readTo access files in Hadoop HDFS, you can use various command line tools provided by Hadoop such as Hadoop File System shell (hdfs dfs), Hadoop File System shell (hadoop fs), or Java APIs like FileSystem and Path classes.You can use the HDFS command shell to navigate through the file system and perform operations like creating directories, uploading files, downloading files, etc.
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9 min readHadoop Big Data utilizes various methodologies to process and analyze large datasets. Some of the commonly used methodologies include:MapReduce: This is a programming model that processes large volumes of data in parallel on a distributed cluster of servers. It divides the input data into smaller chunks, processes them independently, and then combines the results to generate the final output.
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5 min readThe best place to store multiple small files in Hadoop is the Hadoop Distributed File System (HDFS). HDFS is designed to efficiently handle large numbers of small files by splitting them into blocks and distributing them across multiple nodes in the Hadoop cluster. This allows for better storage utilization and faster processing of small files.
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4 min readIn a Hadoop cluster, finding IP address reducer machines involves identifying the nodes where the reduce tasks are executed. These reducer machines are responsible for processing and aggregating the outputs from various mapper tasks in the cluster.To find the IP addresses of the reducer machines in a Hadoop cluster, you can check the configuration files such as mapred-site.xml or yarn-site.xml, which contain the settings for the job tracker or resource manager respectively.