You configure your hadoop cluster with mapreduce V1 (MRv1) along with HDFS high availability (HA) Quorum-based storage. On which nodes should you configure and run your journal node daemon(s) to…

Question

Options

• Astandby namenode, jobtracker, resourcemanager
• BJobtracker
• Cstandby namenode
• DNamenode
• ENamenode and standby namenode
• FNamenode, standby namenode and jobtracker
• GOn each datanode

• A
  86% (24)
• C
  4% (1)
• D
  7% (2)
• G
  4% (1)

Explanation

• JournalNode machines - the machines on which you run the JournalNodes. The JournalNode daemon is relatively lightweight, so these daemons may reasonably be collocated on machines with other Hadoop daemons, for example NameNodes, the JobTracker, ResourceManager. Note: There must be at least 3 JournalNode daemons, since edit log modifications must be written to a majority of JNs. This will allow the system to tolerate the failure of a single machine. * In order to deploy an HA cluster, you should prepare the following: / NameNode machines / JournalNode machines * Quorum-based Storage Quorum-based Storage refers to the HA implementation that uses Quorum Journal Manager In order for the Standby node to keep its state synchronized with the Active node in this implementation, both nodes communicate with a group of separate daemons called JournalNodes. When any namespace modification is performed by the Active node, it durably logs a record of the modification to a majority of these JournalNodes. The Standby node is capable of reading the edits from the JournalNodes, and is constantly watching them for changes to the edit log. As the Standby Node sees the edits, it applies them to its own namespace. In the event of a failover, the Standby will ensure that it has read all of the edits from the JournalNodes before promoting itself to the Active state. This ensures that the namespace state is fully synchronized before a failover occurs. In order to provide a fast failover, it is also necessary that the Standby node has up-to-date information regarding the location of blocks in the cluster. In order to achieve this, the DataNodes are configured with the location of both NameNodes, and they send block location information and heartbeats to both.

No community discussion yet for this question.