Spark I/O error constructing remote block - hadoop

Question

I want to create an home-made spark cluster with two computer in the same network. The setup is the following:
A) 192.168.1.9 spark master with hadoop hdfs installed
Hadoop has this core-site.xml
<configuration>
<property>
<name>hadoop.tmp.dir</name>
<value>/app/hadoop/tmp</value>
</property>
<property>
<name>fs.defaultFS</name>
<value>hdfs://0.0.0.0:9000</value>
</property>
</configuration>
B) 192.168.1.6 with spark only (slave)
From B I want to access to a file in A's hadoop hdfs using the spark command:
...
# Load files
file_1 = "input_1.pkl"
file_2 = "input_2.pkl"
hdfs_base_path = "hdfs://192.168.1.9:9000/folderx/"
sc.addFile(hdfs_base_path + file_1)
sc.addFile(hdfs_base_path + file_2)
# Get files back
with open(SparkFiles.get(file_1), 'rb') as fw:
// use fw
However, if I want to test the program in B, when I execute the program in B using the command:
./spark-submit --master local program.py
The output is the following:
17/07/25 19:02:51 INFO SparkContext: Added file hdfs://192.168.1.9:9000/bigdata/input_1_new_grid.pkl at hdfs://192.168.1.9:9000/bigdata/input_1_new_grid.pkl with timestamp 1501002171301
17/07/25 19:02:51 INFO Utils: Fetching hdfs://192.168.1.9:9000/bigdata/input_1_new_grid.pkl to /tmp/spark-838c3774-36ec-4db1-ab01-a8a8c627b100/userFiles-b4973f80-be6e-4f2e-8ba1-cd64ddca369a/fetchFileTemp1979399086141127743.tmp
17/07/25 19:02:51 WARN BlockReaderFactory: I/O error constructing remote block reader.
java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
And later:
17/07/25 19:02:51 WARN DFSClient: Failed to connect to /127.0.0.1:50010 for block, add to deadNodes and continue. java.net.ConnectException: Connection refused
java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
The program tries to access 127.0.0.1:50010, and it is wrong. Should I install hadoop also in B? If it is not necessary, what is the correct configuration? Thank you!

Answer 1

btw, just in case anyone comes to find some sort of solution, I fixed my issue by pointed quickstart.cloudera to real IP address instead of 127.0.0.1.
The default /etc/hosts is
127.0.0.1 quickstart.cloudera quickstart localhost localhost.domain
What you want is
127.0.0.1 localhost localhost.domain
xxxIP_Address_oF_YOUR_VM quickstart.cloudera quickstart
You may want to modify /usr/bin/cloudera-quickstart-ip as well, because every time you restart your VM, the hosts file may got reset again.