HDFS high availability in Hadoop - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start the HDFS NameNode in high availability mode.

Hadoop

hdfs --daemon start [1]

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Asecondarynamenode

Bjournalnode

Cdatanode

Dnamenode

Attempts:

3 left

💡 Hint

Common Mistakes

Starting datanode instead of namenode

Starting secondarynamenode which is not used in HA

Starting journalnode which is for shared edits

The NameNode is the master node in HDFS and must be started to enable high availability.

2fill in blank

medium

Complete the command to check the status of the HDFS high availability setup.

Hadoop

hdfs haadmin -[1]

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AgetServiceState

Bfailover

CtransitionToActive

DrefreshNodes

Attempts:

3 left

💡 Hint

Common Mistakes

Using failover which triggers failover instead of checking status

Using transitionToActive which changes state

Using refreshNodes which refreshes datanode info

The getServiceState option shows if a NameNode is active or standby in HA.

3fill in blank

hard

Fix the error in the command to perform a manual failover in HDFS HA.

Hadoop

hdfs haadmin -failover [1]

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Ann1

Bnn2

Attempts:

3 left

💡 Hint

Common Mistakes

Providing two NameNode names causing syntax error

Using the standby NameNode as source incorrectly

The failover command requires the source NameNode only, not two arguments.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps each NameNode to its HA state.

Hadoop

states = {nn: 'hdfs haadmin -getServiceState ' + nn for nn in {{BLANK_2}}

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Ann

B['nn1', 'nn2']

C['nn1', 'nn2', 'nn3']

Dnamenodes

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong variable name in the comprehension

Using an incorrect list of NameNodes

The command uses each NameNode name to get its state, iterating over the list of two NameNodes.

5fill in blank

hard

Fill all three blanks to create a dictionary of NameNodes with their HA states, filtering only active ones.

Hadoop

active_nodes = { [1]: 'hdfs haadmin -getServiceState ' + [2] for [3] in ['nn1', 'nn2'] if 'hdfs haadmin -getServiceState ' + [3] == 'active' }

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Ann

Dnode

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently

Not calling the getServiceState command correctly

The comprehension maps each NameNode to its state, iterating over the list and filtering for active nodes only.