1102 お客様のコメント
質問 1：
You have installed a cluster running HDFS and MapReduce version 2 (MRv2) on YARN. You have no afs.hosts entry()ies in your hdfs-alte.xml configuration file. You configure a new worker node by setting fs.default.name in its configuration files to point to the NameNode on your cluster, and you start the DataNode daemon on that worker node.
What do you have to do on the cluster to allow the worker node to join, and start storing HDFS blocks?
A. Nothing; the worker node will automatically join the cluster when the DataNode daemon is started.
B. Restart the NameNode
C. Create a dfs.hosts file on the NameNode, add the worker node's name to it, then issue the command hadoop dfsadmin -refreshNodes on the NameNode
D. Without creating a dfs.hosts file or making any entries, run the command hadoop dfsadmin -refreshHadoop on the NameNode
正解：D
質問 2：
You are the hadoop fs -put command to add a file "sales.txt" to HDFS. This file is small enough that it fits into a single block, which is replicated to three nodes in your cluster (with a replication factor of 3). One of the nodes holding this file (a single block) fails. How will the cluster handle the replication of this file in this situation/
A. The file will be re-replicated automatically after the NameNode determines it is under replicated based on the block reports it receives from the DataNodes
B. This file will be immediately re-replicated and all other HDFS operations on the cluster will halt until the cluster's replication values are restored
C. The cluster will re-replicate the file the next time the system administrator reboots the NameNode daemon (as long as the file's replication doesn't fall two)
D. The file will remain under-replicated until the administrator brings that nodes back online
正解：B
質問 3：
You want a node to only swap Hadoop daemon data from RAM to disk when absolutely necessary. What should you do?
A. Delete the /dev/vmswap file on the node
B. Set vm.swappiness to o in /etc/sysctl.conf
C. Set the ram.swap parameter to o in core-site.xml
D. Delete the /swapfile file on the node
E. Delete the /etc/swap file on the node
正解：B
質問 4：
For each YARN Job, the Hadoop framework generates task log files. Where are Hadoop's files stored?
A. On the local disk of the slave node running the task
B. Cached by the NodeManager managing the job containers, then written to a log directory on the NameNode
C. In HDFS, In the directory of the user who generates the job
D. Cached In the YARN container running the task, then copied into HDFS on fob completion
正解：A
解説: (Pass4Test メンバーにのみ表示されます)
質問 5：
Identify two features/issues that YARN is designed to address:
A. HDFS latency
B. Standardize on a single MapReduce API
C. Resource pressures on the JobTracker
D. Reduce complexity of the MapReduce APIs
E. Single point of failure in the NameNode
F. Ability to run frameworks other than MapReduce, such as MPI
正解：C,F
You have installed a cluster running HDFS and MapReduce version 2 (MRv2) on YARN. You have no afs.hosts entry()ies in your hdfs-alte.xml configuration file. You configure a new worker node by setting fs.default.name in its configuration files to point to the NameNode on your cluster, and you start the DataNode daemon on that worker node.
What do you have to do on the cluster to allow the worker node to join, and start storing HDFS blocks?
A. Nothing; the worker node will automatically join the cluster when the DataNode daemon is started.
B. Restart the NameNode
C. Create a dfs.hosts file on the NameNode, add the worker node's name to it, then issue the command hadoop dfsadmin -refreshNodes on the NameNode
D. Without creating a dfs.hosts file or making any entries, run the command hadoop dfsadmin -refreshHadoop on the NameNode
正解：D
質問 2：
You are the hadoop fs -put command to add a file "sales.txt" to HDFS. This file is small enough that it fits into a single block, which is replicated to three nodes in your cluster (with a replication factor of 3). One of the nodes holding this file (a single block) fails. How will the cluster handle the replication of this file in this situation/
A. The file will be re-replicated automatically after the NameNode determines it is under replicated based on the block reports it receives from the DataNodes
B. This file will be immediately re-replicated and all other HDFS operations on the cluster will halt until the cluster's replication values are restored
C. The cluster will re-replicate the file the next time the system administrator reboots the NameNode daemon (as long as the file's replication doesn't fall two)
D. The file will remain under-replicated until the administrator brings that nodes back online
正解：B
質問 3：
You want a node to only swap Hadoop daemon data from RAM to disk when absolutely necessary. What should you do?
A. Delete the /dev/vmswap file on the node
B. Set vm.swappiness to o in /etc/sysctl.conf
C. Set the ram.swap parameter to o in core-site.xml
D. Delete the /swapfile file on the node
E. Delete the /etc/swap file on the node
正解：B
質問 4：
For each YARN Job, the Hadoop framework generates task log files. Where are Hadoop's files stored?
A. On the local disk of the slave node running the task
B. Cached by the NodeManager managing the job containers, then written to a log directory on the NameNode
C. In HDFS, In the directory of the user who generates the job
D. Cached In the YARN container running the task, then copied into HDFS on fob completion
正解：A
解説: (Pass4Test メンバーにのみ表示されます)
質問 5：
Identify two features/issues that YARN is designed to address:
A. HDFS latency
B. Standardize on a single MapReduce API
C. Resource pressures on the JobTracker
D. Reduce complexity of the MapReduce APIs
E. Single point of failure in the NameNode
F. Ability to run frameworks other than MapReduce, such as MPI
正解：C,F
工藤** -
Pass4TestのCCA-505は所詮基本情報の縮小版かと思いきや、基本情報と同じくらいいろいろな側面の知識が必要なのですね。