Hadoop Cluster Administration Course: Guide for Hadoop Admin

Download CentOS by navigating to the official download page, selecting the 64-bit dvd image, choosing a mirror and version, and starting the download.

Set up a virtual machine in VirtualBox by naming the instance, selecting Linux 32-bit or 64-bit, enabling virtualization in BIOS, and configuring RAM and a dynamically allocated virtual hard drive.

Configure a virtual machine by attaching a CentOS ISO: adjust storage, uncheck floppy, select a virtual CD image, load the ISO file, and set the network adapter.

Start and configure two virtual machines for a hadoop cluster, assign each an IP and hostname, update /etc/hosts to enable bidirectional communication, and verify connectivity with ping.

Shows how to install Java on virtual machines, including logging in, navigating directories, and running sudo yum install java to install a custom JDK.

Generate ssh key pairs across machines to enable passwordless, secure remote access. Configure a common user, install OpenSSH, and manage private and public keys for trusted logins.

Distribute the ssh public key across machines by copying it into each remote machine's authorized keys, enabling secure, key-based access and updating the known hosts as connections are established.

Set up the Java environment by confirming the Java version, exporting JAVA_HOME, updating bashrc, and sourcing it to apply changes, ensuring Java 1.6.0 is active.

Explore the directory structure, inspect bin and conf files like hdfs-site and mapred-site, and set up a pseudo distributed cluster to start with Hadoop.

Format the namenode by setting proper permissions on the Hadoop directory, log in as the hadoop user, and initialize the namespace to support the distributed file system.

Start the daemons from the bin directory in pseudo distributed mode on a single machine, and monitor dfs namenode, datanode, jobtracker, and tasktracker.

Learn how to check the Hadoop file system using the dfs file system checking utility and related commands, inspecting blocks, replication, and directory contents.

Create the elementary directory, copy a local file into it, and verify via dfs commands that the directory and file exist in the file system.

Learn how to manage Hadoop daemons, start and stop the NameNode and DataNode, and format the NameNode to recover from an inconsistent storage directory, ensuring a clean cluster restart.

create a parent directory to permanently store data within the directory tree, configure its ownership and permissions, and navigate through the abc and ebc directories to verify structure.

Learn to run admin commands for cluster administration using the Hadoop dfs admin client, explore dfs commands, and generate a detailed report showing capacity, used, remaining, and replica blocks.

Learn how to access and monitor a Hadoop cluster via the browser interface, create directories, copy data with HDFS commands, and view job tracker and task tracker details.

Learn how data is stored and distributed in the fully distributed mode of a Hadoop cluster by navigating directories, creating blocks and metafiles, and verifying blocks across machines.

Learn how under replicated blocks occur in a Hadoop cluster, observe block creation and replication across data nodes, and verify status with the report command; note NameNode directory recovery.

Learn how to handle a poorly distributed Hadoop cluster by observing block replication, automatic recovery, and adding a new data node, plus validating SSH connections and network health.

Learn how to commission and decommission nodes in a Hadoop cluster, manage daemons across master and slave machines, and start or stop daemons while tracking added or removed servers.

Explore the Metasave command in the Hadoop cluster for a DFS report that shows disk space, blocks, and replication status. Learn to verify file presence and block state.

Explore how to dynamically write data with different replication factors in Hadoop by creating a directory, copying a file into the DFS, and setting its replication to one, then verifying.

Rack awareness distributes blocks across racks to boost availability and performance, guiding replicas to different racks so not all copies reside on one rack.

Learn how to enable rack awareness in a Hadoop cluster by identifying machine IPs, configuring permissions, and using scripts to track node information and rack mappings.

Learn how the secondary namenode acts as a checkpoint process, merging edit logs with the fsimage, loading updates in memory, and copying changes to the primary namenode to minimize downtime.

Explore how the secondary namenode operates in a Hadoop cluster, focusing on checkpoint intervals, current versus previous times, and image-based status updates every 10 minutes.

Explore how adding and deleting files in a Hadoop cluster updates the fsimage, affects metadata and size, and how to view these changes through the browser interface and commands.

Learn how to manually connect to the namenode by stopping the secondary namenode to release directory locks, perform updates, and verify changes before restarting the secondary namenode.

Explore safemode in Hadoop, a read-only state where the name node locks the file system namespace in memory and defers block replication until the system is ready.

Learn to manage edits on a filesystem image by using a namespace, merging changes into the filesystem image, and saving updates while safe mode restrictions apply.

Decommission nodes in a Hadoop cluster by editing the exclude file and running a report to identify target machines. Ensure replication and namenode coordination prevent inconsistency.

Learn how to commission and decommission Hadoop cluster nodes, maintain availability with a minimum two-machine setup, and handle recommissioning to recover from node failures.

The hdfs balancer analyzes block placement and moves blocks to balance disk usage across the cluster, using a default 10 percent threshold or a custom value.

Explore how to restore the data within a Hadoop cluster as part of the Hadoop cluster administration course, focusing on data recovery concepts.

The lecture explains how hdfs trash preserves deleted files in the trash directory, how you can retrieve them, and how to permanently delete by bypassing the trash to reclaim storage.

Distcp, the distributed copy tool, expands a list of files and directories into map tasks and copies partitions across cluster nodes using MapReduce.

Explore practical data backup with distcp and cp, learning how to copy files within a cluster and across clusters for reliable Hadoop data protection.

Learn to use distcp across a Hadoop cluster to copy data between data nodes and back up files across clusters.

Explore the file system in the browser interface, examining folders, log files, and history to understand job ids, execution status, and sample files within disk tcp logs.

Learn to recover a crashed namenode by inspecting running processes, stopping secondary nodes, and restoring the fsimage from the secondary using copy operations and checkpoint data.

Learn to start the second datanode by updating configuration files, cleaning up blocks, and restarting the datanode service to restore replication across two nodes.

Learn how to recover a down namenode on an old Hadoop cluster by stopping services, restoring configurations, and restarting processes to resume replication and return to normal operation.

Execute forced checkpointing to update and recover metadata, realign renamed node directories, and validate the checkpoint and downloaded image file in the Hadoop cluster.

Learn to run a Hadoop cluster from multiple data parts by updating configuration files, stopping daemons, creating and wiring multiple data directories, and setting proper ownership and permissions.

Understand how a network file system enables sharing directories and accessing remote files as if they were local, with a client-server architecture to view and update files.

Install and configure the NFS server, create a shared directory, grant read and write access via exports with sync, and start the NFS service to enable shared storage.

Start the cluster by configuring a shared data directory and exporting it for sharing across nodes and clients, then verify the shared storage and the job and task trackers.

Delete the namenode's primary path and restart the namenode, then resolve directory inconsistencies by removing the primary directory from all references and checking logs.

Learn how to recover metadata from a secondary location to the primary location by recreating directories, setting ownership, and importing checkpoints to restore the primary metadata.