6.2.4 Checking the Connection to the Slave Server

Before building the second and subsequent slave servers, check that the first already installed slave server can connect correctly to the master server.

Check this on the primary master server. Also make sure to execute with root permissions.

Backup the slave server definition file (/etc/opt/FJSVbdpp/conf/slaves) so that it can be edited to check the connection of the first slave server.
```
# cp /etc/opt/FJSVbdpp/conf/slaves /etc/opt/FJSVbdpp/conf/slaves.bak <Enter>
```
Edit the slave server definition file, and leaving only the slave server that is to be checked for connection, delete the other slave servers.
Before editing:
```
# cat /etc/opt/FJSVbdpp/conf/slaves <Enter>
slave1,slave2,slave3,slave4,slave5
```
After editing:
```
# cat /etc/opt/FJSVbdpp/conf/slaves <Enter>
slave1
```
Execute bdpp_changeslaves command to effect the changes that were made to the slave server definition file.
```
# /opt/FJSVbdpp/bin/bdpp_changeslaves <Enter>
```
Execute the bdpp_start command to start the Hadoop of this product.
```
# /opt/FJSVbdpp/bin/bdpp_start <Enter>
```

Execute the bdpp_stat command to display the status of the Hadoop of this product and check whether or not TaskTracker is running on the slave server.

# /opt/FJSVbdpp/bin/bdpp_stat -all <Enter>
cluster mapred  30595   jobtracker 
slave1  mapred  11381   tasktracker          <--  Check that TaskTracker is started at slave1.
bdpp:  INFO : 003:  bdpp Hadoop JobTracker is alive.

Run the Hadoop job to check operation.
Use the sample that came with Hadoop (teragen, terasort, etc.) to check the operation of the Hadoop job.
Execute the bdpp_stop command to stop the Hadoop of this product.
```
# /opt/FJSVbdpp/bin/bdpp_stop <Enter>
```
After checking the connection between the master server and the first slave server, restore the backup of the slave server definition file.
```
# rm -fr /etc/opt/FJSVbdpp/conf/slaves <Enter>
# cp /etc/opt/FJSVbdpp/conf/slaves.bak /etc/opt/FJSVbdpp/conf/slaves <Enter>
```
Execute bdpp_changeslaves command to effect the changes that were made to the slave server definition file again.
```
# /opt/FJSVbdpp/bin/bdpp_changeslaves <Enter>
```

See

Refer to "A.4 bdpp_changeslaves" for information on the bdpp_changeslaves command.
Refer to "A.14 bdpp_start" for information on the bdpp_start command.
Refer to "A.15 bdpp_stat" for information on the bdpp_stat command.
Refer to "Chapter 10 Executing and Stopping Jobs" for information on executing Hadoop jobs.
Refer to "A.16 bdpp_stop" for information on the bdpp_stop command.