I have an old Hadoop install that I'm looking to update to Hadoop 2. In the
old setup, I have a $HADOOP_HOME/conf/masters file that specifies the
secondary namenode.
Looking through the Hadoop 2 documentation I can't find any mention of a
"masters" file, or how to setup a secondary namenode.
Any help in the right direction would be appreciated.
The slaves and masters files in the conf folder are only used by some scripts in the bin folder like start-mapred.sh, start-dfs.sh and start-all.sh scripts.
These scripts are a mere convenience so that you can run them from a single node to ssh into each master / slave node and start the desired hadoop service daemons.
You only need these files on the name node machine if you intend to launch your cluster from this single node (using password-less ssh).
Alternatively, You can also start an Hadoop daemon manually on a machine via
bin/hadoop-daemon.sh start [namenode | secondarynamenode | datanode | jobtracker | tasktracker]
In order to run the secondary name node, use the above script on the designated machines providing the 'secondarynamenode' value to the script
See #pwnz0r 's 2nd comment on answer on How separate hadoop secondary namenode from primary namenode?
To reiterate here:
In hdfs-site.xml:
<property>
<name>dfs.secondary.http.address</name>
<value>$secondarynamenode.full.hostname:50090</value>
<description>SecondaryNameNodeHostname</description>
</property>
I am using Hadoop 2.6 and had to use
<property>
<name>dfs.secondary.http.address</name>
<value>secondarynamenode.hostname:50090</value>
</property>
for further details refer https://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml
Update hdfs-site.xml file by updating and adding following property
cd $HADOOP_HOME/etc/hadoop
sudo vi hdfs-site.xml
Then paste these lines into configuration tag
<property>
<name>dfs.secondary.http.address</name>
<value>hostname:50090</value>
</property>
Related
We have 4 datanode HDFS cluster ...there is large amount of space available on each data node of about 98gb ...but when i look at the datanode information .. it's only using about 10gb and running out of space ...
How can we make it use all the 98gb and not run out of space as indicated in image
this is the disk space configuration
this is the hdfs-site.xml on name node
<property>
<name>dfs.name.dir</name>
<value>/test/hadoop/hadoopinfra/hdfs/namenode</value>
</property>
this is the hdfs-site.xml under data node
<property>
<name>dfs.data.dir</name>
<value>/test/hadoop/hadoopinfra/hdfs/datanode</value>
</property>
Eventhough /test has 98GB and hdfs is configured to use it it's not using it
Am I missing anything while doing the configuration changes? And how can we make sure 98GB is used?
According to this Hortonworks Community Portal link, the steps to amend your Data Node directory are as follows:
Stop the cluster.
Go to the ambari HDFS configuration and edit the datanode directory configuration: Remove /hadoop/hdfs/data and /hadoop/hdfs/data1. Add [new directory location].
Login into each datanode (via SSH) and copy the contents of /data and /data1 into the new directory.
Change the ownership of the new directory and everything under it to “hdfs”.
Start the cluster.
I'm assuming that you're technically already up to Step 2 since you've displayed your correctly configured core-site.xml files in the original question. Make sure you've done the other steps and that all Hadoop services have been stopped. From there, change the ownership to the user running Hadoop (typically hdfs but I've worked in a place where root was running the Hadoop processes) and you should be good to go :)
I have a hadoop cluster on aws and I am trying to access it from outside the cluster through a hadoop client. I can successfully hdfs dfs -ls and see all contents but when I try to put or get a file I get this error:
Exception in thread "main" java.lang.NullPointerException
at org.apache.hadoop.fs.FsShell.displayError(FsShell.java:304)
at org.apache.hadoop.fs.FsShell.run(FsShell.java:289)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:84)
at org.apache.hadoop.fs.FsShell.main(FsShell.java:340)
I have hadoop 2.6.0 installed in both my cluster and my local machine. I have copied the conf files of the cluster to the local machine and have these options in hdfs-site.xml (along with some other options).
<property>
<name>dfs.client.use.datanode.hostname</name>
<value>true</value>
</property>
<property>
<name>dfs.permissions.enable</name>
<value>false</value>
</property>
My core-site.xml contains a single property in both the cluster and the client:
<property>
<name>fs.defaultFS</name>
<value>hdfs://public-dns:9000</value>
<description>NameNode URI</description>
</property>
I found similar questions but wasn't able to find a solution to this.
How about you SSH into that machine?
I know this is a very bad idea but to get the work done, you can first copy that file on machine using scp and then SSH into that cluster/master and do hdfs dfs -put on that copied local file.
You can also automate this via a script but again, this is just to get the work done for now.
Wait for someone else to answer to know the proper way!
I had similar issue with my cluster when running hadoop fs -get and I could resolve it. Just check if all your data nodes are resolvable using FQDN(Fully Qualified Domain Name) from your local host. In my case nc command was successful using ip addresses for data nodes but not with host name.
run below command :
for i in cat /<host list file>; do nc -vz $i 50010; done
50010 is default datanode port
when you run any hadoop command it try to connect to data nodes using FQDN and thats where it gives this weird NPE.
Do below export and run your hadoop command
export HADOOP_ROOT_LOGGER=DEBUG,console
you will see this NPE comes when it is trying to connect to any datanode for data transfer.
I had a java code which was also doing hadoop fs -get using APIs and there ,exception was more clearer
java.lang.Exception: java.nio.channels.UnresolvedAddressException
Let me know if this helps you.
I have limited capacity in /tmp so I want to move all the intermediate output of mapred in a bigger partition, say /home/hdfs/tmp_data .
If I understand correctly, I just need to set
<property>
<name>mapred.child.tmp</name>
<value>/home/hdfs/tmp_data</value>
in mapred-site.xml
I restart the cluster through Ambari, I check everything is written in the conf file,
however, when I run a pig script, it keeps writing in:
/tmp/hadoop-hdfs/mapred/local/taskTracker/hdfs/jobcache/job_localXXX/attempt_YY/output
I have also modified hadoop.tmp.dir in core-site.xml to be /home/hdfs/tmp_data , but nothing changes.
Is there any parameter that overwrite my settings?
Try override the following property in tasktracker nodes mapred-site.xml file and restart it.
<property>
<name>mapred.local.dir/name>
<value>/home/hdfs/tmp_data</value>
</property>
I have installed Hadoop in pseudo distributed mode on my laptop, OS is Ubuntu.
I have changed paths where hadoop will store its data (by default hadoop stores data in /tmp folder)
hdfs-site.xml file looks as below :
<property>
<name>dfs.data.dir</name>
<value>/HADOOP_CLUSTER_DATA/data</value>
</property>
Now whenever I restart machine and try to start hadoop cluster using start-all.sh script, data node never starts. I confirmed that data node is not start by checking logs and by using jps command.
Then I
Stopped cluster using stop-all.sh script.
Formatted HDFS using hadoop namenode -format command.
Started cluster using start-all.sh script.
Now everything works fine even if I stop and start cluster again. Problem occurs only when I restart machine and try to start the cluster.
Has anyone encountered similar problem?
Why this is happening and
How can we solve this problem?
By changing dfs.datanode.data.dir away from /tmp you indeed made the data (the blocks) survive across a reboot. However there is more to HDFS than just blocks. You need to make sure all the relevant dirs point away from /tmp, most notably dfs.namenode.name.dir (I can't tell what other dirs you have to change, it depends on your config, but the namenode dir is mandatory, could be also sufficient).
I would also recommend using a more recent Hadoop distribution. BTW, the 1.1 namenode dir setting is dfs.name.dir.
For those who use hadoop 2.0 or above versions config file names may be different.
As this answer points out, go to the /etc/hadoop directory of your hadoop installation.
Open the file hdfs-site.xml. This user configuration will override the default hadoop configurations, that are loaded by the java classloader before.
Add dfs.namenode.name.dir property and set a new namenode dir (default is file://${hadoop.tmp.dir}/dfs/name).
Do the same for dfs.datanode.data.dir property (default is file://${hadoop.tmp.dir}/dfs/data).
For example:
<property>
<name>dfs.namenode.name.dir</name>
<value>/Users/samuel/Documents/hadoop_data/name</value>
</property>
<property>
<name>dfs.datanode.data.dir</name>
<value>/Users/samuel/Documents/hadoop_data/data</value>
</property>
Other property where a tmp dir appears is dfs.namenode.checkpoint.dir. Its default value is: file://${hadoop.tmp.dir}/dfs/namesecondary.
If you want, you can easily also add this property:
<property>
<name>dfs.namenode.checkpoint.dir</name>
<value>/Users/samuel/Documents/hadoop_data/namesecondary</value>
</property>
I am trying to run hadoop as a root user, i executed namenode format command hadoop namenode -format when the Hadoop file system is running.
After this, when i try to start the name node server, it shows error like below
13/05/23 04:11:37 ERROR namenode.FSNamesystem: FSNamesystem initialization failed.
java.io.IOException: NameNode is not formatted.
at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:330)
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:100)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:411)
I tried to search for any solution, but cannot find any clear solution.
Can anyone suggest?
Thanks.
DFS needs to be formatted. Just issue the following command after stopping all and then restart.
hadoop namenode -format
Cool, i have found the solution.
Stop all running server
1) stop-all.sh
Edit the file /usr/local/hadoop/conf/hdfs-site.xml and add below configuration if its missing
<property>
<name>dfs.data.dir</name>
<value>/app/hadoop/tmp/dfs/name/data</value>
<final>true</final>
</property>
<property>
<name>dfs.name.dir</name>
<value>/app/hadoop/tmp/dfs/name</value>
<final>true</final>
</property>
Start both HDFS and MapReduce Daemons
2) start-dfs.sh
3) start-mapred.sh
Then now run the rest of the steps to run the map reduce sample given in this link
Note : You should be running the command bin/start-all.sh if the direct command is not running.
format hdfs when namenode stop.(just like the top answer).
I add some more details.
FORMAT command will check or create path/dfs/name, and initialize or reinitalize it.
then running start-dfs.sh would run namenode, datanode, then namesecondary.
when namenode check not exist path/dfs/name or not initialize, it occurs a fatal error, then exit.
that's why namenode not start up.
more details you can check HADOOP_COMMON/logs/XXX.namenode.log
Make sure the directory you've specified for your namenode is completely empty. Something like a "lost+found" folder in said directory will trigger this error.
hdfs-site.xml your value is wrong. You input the wrong folder that's why is not starting the name node.
First mkdir [folder], then set hdfs-site.xml then format
make sure that the directory to name(dfs.name.dir) and data (dfs.data.dir) folder is correctly listed in hdfs-site.xml
Formatting namenode worked for me
bin/hadoop namenode -format