I have copied a file from a local to the hdfs file system and the file got copied -- /user/hduser/in
hduser#vagrant:/usr/local/hadoop/hadoop-1.2.1$ bin/hadoop fs -copyFromLocal /home/hduser/afile in
Question:-
1.How does hadoop by default copies the file to this directory -- /user/hduser/in ...Where is this mapping specified in the conf file?
If you write the command like above, the file gets copied to your user's HDFS home directory, which is /home/username. See also here: HDFS Home Directory.
You can use an absolute pathname (one starting with "/") just like in a Linux filesystem, if you want to write the file to a different location.
Are u using a default vm? Basically if you configure hadoop from binaries without using the preconfigure yum package. It doesnt have a default path. But if you use yum via hortin or cloudera vm. It comes with default path i guess
Check the hdfs-site.xml to see the default fs path. So "/" will point to the base URL set in the above mentioned XML. Any folder mentioned in the command without the use of home path will be appended to that.
hadoop picks the default path defined in hdfs-site.xml and write data.
below image clear how writes works in HDFS.
Related
I'm trying to add hive-contrib-0.10.0.jar in hive using ADD JAR hive-contrib-0.10.0.jar command but it always saying hive-contrib-0.10.0.jar does not exist.
I'm using HDP 2.1 version right now. I also added this jar file into /user/root folder using hue and run the command
ADD JAR hdfs:///hive-contrib-0.10.0.jar
but it giving me same error jar file doesn't exist.
Is there any way to solve this problem.
Where should I keep this jar file so that it will run successfully and what will be the command to be used?
upload the JAR file into hdfs path
Add the JAR File using Add command and HDFS full PATH
Example:
hadoop fs -put ~/Downloads/hive.jar /lib/
open hive shell
add jar hdfs:///lib/hive.jar
I see following issues with your approach. Before adding make sure you are able to list the file on Local file system or hdfs where ever it exists.
The jar you are trying to add is by default in hive class path as its part of $HIVE_HOME/lib (on local file system where ever you have hive client/service installed)
on the other hand in regards to your question about how to add jars in hive, we can add using local file system or hadoop distributed file system (HDFS)
Add jar file:///root/hive-contrib-0.10.0.jar (Given that you copied this jar on LFS root directory)
Add jar hdfs://<namenode_hostname>:8020/user/root/hive-contrib-0.10.0.jar (Given that you copied to HDFS root home)
if you want to permanently add the jars you need to do the following.
1. Hive-site.xml ( /etc/hive/conf )
<property>
<name>hive.aux.jars.path</name>
<value>file:///mnt1/hive-jars/hive-contrib-2.1.1.jar</value>
</property>
add hive-contrib-2.1.1.jar to the path "/mnt1/hive-jars" configured in hive-site.xml
This should ideally work after restarting hive-server2.
3. sudo stop hive-server2
4. sudo start hive-server2
But sometimes it does not work. i am not sure why so you can use the following dirty way.
put your jar file in the following path so that hive automatically picks it up while restart.
add hive-contrib-2.1.1.jar to /usr/lib/hive-hcatalog/share/hcatalog
sudo stop hive-server2
sudo start hive-server2
I have read these answers above which was very useful. And I combined all into one solution:
put jars into local disk and give read/write permission
chmod -R 777 /tmp/json.jar
upload to hdfs file system and give permissions too:
hdfs dfs -put /tmp/json.jar hdfs://1.1.1.1:8020/jars/
hdfs dfs -chmod -R 777 hdfs://1.1.1.1:8020/jars/
add jar into hive env.
add jar hdfs://1.1.1.1:8020/jars/json.jar
You have to give the full path to the jar JAR and not only its name.
Don't guess the location. Check the file system to see that it is there, before trying to add it.
I don't know what's going on here but I am trying to copy a simple file from a directory in my local filesystem to the directory specified for hdfs.
In my hdfs-site.xml I have specified that the directory for hdfs will be /home/vaibhav/Hadoop/dataNodeHadoopData using the following properties -
<name>dfs.data.dir</name>
<value>/home/vaibhav/Hadoop/dataNodeHadoopData/</value>
and
<name>dfs.name.dir</name>
<value>/home/vaibhav/Hadoop/dataNodeHadoopData/</value>
I am using the following command -
bin/hadoop dfs -copyFromLocal /home/vaibhav/ml-100k/u.data /home/vaibhav/Hadoop/dataNodeHadoopData
to copy the file u.data from it's local filesystem location to the directory that I specified as Hdfs directory. But when I do this, nothing happens - no error, nothing. And no file gets copied to the hdsf. Am I doing something wrong? Any permissions issue could be there?
Suggestions needed.
I am using pseudo distributed single node mode.
Also, on a related note, I want to ask that in my map reduce program I have set the configuration to point to the inputFilePath as /home/vaibhav/ml-100k/u.data. So would it not automatically copy the file from given location to hdfs ?
I believe dfs.data.dir and dfs.name.dir have to point to two different and existing directories. Furthermore make sure you have formatted the namenode FS after changing the directories in the configuration.
While copying to HDFS you're incorrectly specifying the target. The correct syntax for copying a local file to HDFS is:
bin/hadoop dfs -copyFromLocal <local_FS_filename> <target_on_HDFS>
Example:
bin/hadoop dfs -copyFromLocal /home/vaibhav/ml-100k/u.data my.data
This would create a file my.data in your user's home directory in HDFS.
Before copying files to HDFS make sure, you master listing directory contents and directory creation first.
I had installed hadoop stable version successfully. but confused while installing hadoop -2.0.0 version.
I want to install hadoop-2.0.0-alpha on two nodes, using federation on both machines. rsi-1, rsi-2 are hostnames.
what should be values of below properties for implementation of federation. Both machines are also used for datanodes too.
fs.defaulFS dfs.federation.nameservices dfs.namenode.name.dir dfs.datanode.data.dir yarn.nodemanager.localizer.address yarn.resourcemanager.resource-tracker.address yarn.resourcemanager.scheduler.address yarn.resourcemanager.address
One more point, in stable version of hadoop i have configuration files under conf folder in installation directory.
But in 2.0.0-aplha version, there is etc/hadoop directory and it doesnt have mapred-site.xml, hadoop-env.sh. do i need to copy conf folder under share folder into hadoop-home directory? or do i need to copy these files from share folder into etc/hadoop directory?
Regards, Rashmi
You can run hadoop-setup-conf.sh in sbin folder. It instructs you step-by-step to configure.
Please remember when it asks you to input the directory path, you should use full link
e.g., when it asks for conf directory, you should input /home/user/Documents/hadoop-2.0.0/etc/hadoop
After completed, remember to check every configuration file in etc/hadoop.
As my experience, I modified JAVA_HOME variable in hadoop-env.sh and some properties in core-site.xml, mapred-site.xml.
Regards
I gave an input to the mapper from a local filesystem.It is running successfully from eclipse,But not running from the cluster as it is unable to find the local input path saying:input path does not exist.Please can anybody help me how to give a local file path to a mapper so that it can run in the cluster and i can get the output in hdfs
This is a very old question. Recently faced the same issue.
I am not aware of how correct this solution is it worked for me though. Please bring to notice if there are any drawbacks of this.Here's what I did.
Reading a solution from the mail-archives, I realised if i modify fs.default.name from hdfs://localhost:8020/ to file:/// it can access the local file system. However, I didnt want this for all my mapreduce jobs. So I made a copy of core-site.xml in a local system folder (same as the one from where I would submit my MR jar to hadoop jar).
and in my Driver class for MR I added,
Configuration conf = new Configuration();
conf.addResource(new Path("/my/local/system/path/to/core-site.xml"));
conf.addResource(new Path("/usr/lib/hadoop-0.20-mapreduce/conf/hdfs-site.xml"));
The MR takes input from local system and writes the output to hdfs:
Running in a cluster requires the data to be loaded into distributed storage (HDFS). Copy the data to HDFS first using hadoop fs -copyFromLocal and then try to trun your job again, giving it the path of the data in HDFS
The question is an interesting one. One can have data on S3 and access this data without an explicit copy to HDFS prior to running the job. In the wordcount example, one would specify this as follows:
hadoop jar example.jar wordcount s3n://bucket/input s3n://bucket/output
What occurs in this is that the mappers read records directly from S3.
If this can be done with S3, why wouldn't hadoop similarly, using this syntax instead of s3n
file:///input file:///output
?
But empirically, this seems to fail in an interesting way -- I see that Hadoop gives a file not found exception for a file that is indeed in the input directory. That is, it seems to be able to list the files in the put directory on my local disk but when it comes time to open them to read the records, the file is not found (or accessible).
The data must be on HDFS for any MapReduce job to process it. So even if you have a source such as local File System or a network path or a web based store (such as Azure Blob Storage or Amazon Block stoage), you would need to copy the data at HDFS first and then run the Job.
The bottom line is that you would need to push the data first to to HDFS and there are several ways depend on data source, you would perform the data transfer from your source to HDFS such as from local file system you would use the following command:
$hadoop -f CopyFromLocal SourceFileOrStoragePath _HDFS__Or_directPathatHDFS_
Try setting the input path like this
FileInputFormat.addInputPath(conf, new Path(file:///the directory on your local filesystem));
if you give the file extension, it can access files from the localsystem
I have tried the following code and got the solution...
Please try it and let me know..
You need to get FileSystem object for local file system and then use makequalified method to return path.. As we need to pass path of local filesystem(no other way to pass this to inputformat), i ve used make qualified, which in deed returns only local file system path..
The code is shown below..
Configuration conf = new Configuration();
FileSystem fs = FileSystem.getLocal(conf);
Path inputPath = fs.makeQualified(new Path("/usr/local/srini/")); // local path
FileInputFormat.setInputPaths(job, inputPath);
I hope this works for your requirement, though it's posted very late.. It worked fine for me.. It does not need any configuration changes i believe..
U might wanna try this by setting the configuration as
Configuration conf=new Configuration();
conf.set("job.mapreduce.tracker","local");
conf.set("fs.default.name","file:///");
After this u can set the fileinputformat with the local path and u r good to go
I am running hadoop with default configuration with one-node cluster, and would like to find where HDFS stores files locally.
Any ideas?
Thanks.
You need to look in your hdfs-default.xml configuration file for the dfs.data.dir setting. The default setting is: ${hadoop.tmp.dir}/dfs/data and note that the ${hadoop.tmp.dir} is actually in core-default.xml described here.
The configuration options are described here. The description for this setting is:
Determines where on the local
filesystem an DFS data node should
store its blocks. If this is a
comma-delimited list of directories,
then data will be stored in all named
directories, typically on different
devices. Directories that do not exist
are ignored.
Seems like for the current version(2.7.1) the dir is
/tmp/hadoop-${user.name}/dfs/data
Based on dfs.datanode.data.dir, hadoop.tmp.dir setting from:
http://hadoop.apache.org/docs/r2.7.1/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml
http://hadoop.apache.org/docs/r2.7.1/hadoop-project-dist/hadoop-common/core-default.xml
As "more recent answer" and to clarify hadoop version numbers:
If you use Hadoop 1.2.1 (or something similar), #Binary Nerd's answer is still true.
But if you use Hadoop 2.1.0-beta (or something similar), you should read the configuration documentation here and the option you want to set is: dfs.datanode.data.dir
For hadoop 3.0.0, the hdfs root path is as given by the property "dfs.datanode.data.dir"
Run this in the cmd prompt, and you will get the HDFS location:
bin/hadoop fs -ls /