I want to create an Oozie workflow to transfer an HDFS file from an HDFS cluster to another server.
Since Oozie can run commands or scripts on any node in a system, is it possible to run a shell script or SFTP on one of the nodes and transfer the file to the destination server.
I think this task can be easily done by performing, from the remote server, a http GET (open operation) on the HDFS file (you can use curl for that).
Anyway, if you want to do it through Oozie, I think you can create a script in charge of moving the desired file from HDFS to the local file system, and then perform a scp in order to move the file within the local file system to the remote file system.
Related
I was learning hadoop and till now I configured 3 Node cluster
127.0.0.1 localhost
10.0.1.1 hadoop-namenode
10.0.1.2 hadoop-datanode-2
10.0.1.3 hadoop-datanode-3
My hadoop Namenode directory looks like below
hadoop
bin
data-> ./namenode ./datanode
etc
logs
sbin
--
--
As I learned that when we upload a large file in the cluster in divide the file into blocks, I want to upload a 1Gig file in my cluster and want to see how it is being stored in datanode.
Can anyone help me with the commands to upload file and see where these blocks are being stored.
First, you need to check if you have Hadoop tools in your path, if not - I recommend integrate them into it.
One of the possible ways of uploading a file to HDFS:hadoop fs -put /path/to/localfile /path/in/hdfs
I would suggest you read the documentation and get familiar with high-level commands first as it will save you time
Hadoop Documentation
Start with "dfs" command, as this one of the most often used commands
Whenever I run a pig script through the java PigServer interface, a fresh copy of pig-XXX.jar is copied to my remote hdfs cluster. Is there a way to avoid this and instead have the pig.jar permanently stored on my cluster?
My local machine does not have an hdfs installation. I want to retrieve files from a remote hdfs cluster. What's the best way to achieve this? Do I need to get the files from hdfs to one of the cluster machines fs and then use ssh to retrieve them? I want to be able to do this programmatically through say a bash script.
Here are the steps:
Make sure there is connectivity between your host and the target cluster
Configure your host as client, you need to install compatible hadoop binaries. Also your host needs to be running using same operating system.
Make sure you have the same configuration files (core-site.xml, hdfs-site.xml)
You can run hadoop fs -get command to get the files directly
Also there are alternatives
If Webhdfs/httpFS is configured, you can actually download files using curl or even your browser. You can write bash scritps if Webhdfs is configured.
If your host cannot have Hadoop binaries installed to be client, then you can use following instructions.
enable password less login from your host to the one of the node on the cluster
run command ssh <user>#<host> "hadoop fs -get <hdfs_path> <os_path>"
then scp command to copy files
You can have the above 2 commands in one script
How can I copy files from remote Unix and Windows servers into HDFS without intermediate staging from the command line?
You can use following command:
hadoop fs -cp /user/myuser/copyTestFolder/* hdfs://remoteServer:8020/user/remoteuser/copyTestFolder/
or vice versa to copy from server to local machine.
You can also read the hadoop documentation.
You can use WebHDFS and cURL to upload files. This will not require having any hadoop binaries on your client, just a cURL or cURL like client. The BigInsights Knowledge Center has information on how to administer the file system using the HttpFS REST APIs.
I want to copy files from a remote server using sftp to an hdfs location directly without copying the files to local. The hdfs location is a secured cluster. Please suggest if this is feasible and how to proceed in that case.
Also I would want to know if there is any other way to connect and copy apart from sftp.
I think the most convenient way (given that your remote machine is able to connect to the hadoop cluster) is to make that remote machine act as an HDFS client. Just ssh to that machine, install the hadoop distribution, configure it properly, then run:
hadoop fs -put /local/path /hdfs/path