CCA-410 · Question #18
Your cluster implements HDFS High Availability (HA). You two NameNodes are named nn01 and nn02. What occurs when you execute the command: Hdfs haadmin -failover nn01 nn02
The correct answer is C. Nn01 is fenced, and nn02 becomes the active NameNode. failover - initiate a failover between two NameNodes This subcommand causes a failover from the first provided NameNode to the second. If the first NameNode is in the Standby state, this command simply transitions the second to the Active state without error. If the first…
Question
Your cluster implements HDFS High Availability (HA). You two NameNodes are named nn01 and nn02. What occurs when you execute the command:
Hdfs haadmin -failover nn01 nn02
Options
- Ann02 becomes the standby NameNode and nn02 becomes the active NameNode
- BNn01 is fenced, and nn01 becomes the active NameNode
- CNn01 is fenced, and nn02 becomes the active NameNode
- DNn01 becomes the standby NameNode and nn02 becomes the active NameNode
How the community answered
(27 responses)- A11% (3)
- B4% (1)
- C81% (22)
- D4% (1)
Explanation
failover - initiate a failover between two NameNodes This subcommand causes a failover from the first provided NameNode to the second. If the first NameNode is in the Standby state, this command simply transitions the second to the Active state without error. If the first NameNode is in the Active state, an attempt will be made to gracefully transition it to the Standby state. If this fails, the fencing methods (as configured by dfs.ha.fencing.methods) will be attempted in order until one of the methods succeeds. Only after this process will the second NameNode be transitioned to the Active state. If no fencing method succeeds, the second NameNode will not be transitioned to the Active state, and an error will be
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