DISTCP Parallel replication
The same version of the Hadoop cluster
Hadoop distcp Hdfs//namenode1/foo Hdfs//namenode2/bar
Different versions of the Hadoop cluster (HDFs version), executed on the writing side
Hadoop distcp Hftp://namenode1:50070/foo Hdfs://namenode2/bar
Archive of
Because HDFs is different from a common file system, Hadoop provides a powerful filesystem API to manipulate HDFs.
The core classes are Fsdatainputstream and Fsdataoutputstream.
Read operation:
We use Fsdatainputstream to read the specified file in HDFs (the first experiment), and we also demonstrate the ability to locate the file location of the class, and then start reading the file from the specified location (the second experiment).
The code i
Hadoop (13), hadoop
1. mahout introduction:
Mahout is a powerful data mining tool and a collection of distributed machine learning algorithms, including the implementation, classification, and clustering of distributed collaborative filtering called Taste. The biggest advantage of Mahout is its hadoop-based implementation, which converts many previous algorithms
Build a Hadoop development environment for Fedora 20
1. configuration information:
Operating System: fedora 20X86
Eclipse version: eclipse-jee-helios-SR2-linux-gtk.tar.gz (preferably use Galileo or Helios, otherwise there may be compatibility issues)
Hadoop version: hadoop-1.1.2.tar.gz
Ant: apache-ant-1.9.3-bin.tar.gz
2. Compile the
First, ready to run the required jar package1) Avro-1.7.4.jar2) Commons-cli-1.2.jar3) Commons-codec-1.4.jar4) Commons-collections-3.2.1.jar5) Commons-compress-1.4.1.jar6) Commons-configuration-1.6.jar7) Commons-io-2.4.jar8) Commons-lang-2.6.jar9) Commons-logging-1.2.jar) Commons-math3-3.1.1.jarOne) Commons-net-3.1.jarCurator-client-2.7.1.jar)Curator-recipes-2.7.1.jar)Gson-2.2.4.jar)Guava-20.0.jar)Hadoop-annotations-2.8.0.jar)
When Hadoop was started today, it was discovered that Datanode could not boot, and the following errors were found in the View log: Java.io.ioexception:file/opt/hadoop/tmp/mapred/system/jobtracker.info could only is replicated to 0 nodes, instead o F 1 at Org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock (fsnamesystem.java:1271) at Org.apache.hadoop.hdfs.server.namenode.NameNode.addBl
This morning, I helped a new person remotely build a hadoop cluster (1. in versions X or earlier than 0.22), I am deeply touched. Here I will write down the simplest Apache hadoop construction method and provide help to new users. I will try my best to explain it in detail. Click here to view the avatorhadoop construction steps.
1. Environment preparation:
1 ). machine preparation: the target machine must b
What is hadoop?
Before doing something, the first step is to know what, then why, and finally how ). However, after many years of project development, many developers get used to how first, then what, and finally why. This will only make them impetuous, at the same time, technologies are often misused in unsuitable scenarios.
The core designs in the hadoop framework are mapreduce and HDFS. The idea of mapre
Hadoop FS: The widest range of users can operate any file system.
Hadoop DFS and HDFs dfs: only HDFs file system related (including operations with local FS) can be manipulated, the former has been deprecated, generally using the latter.
The following reference from StackOverflow
Following are the three commands which appears same but have minute differences Hadoop
Hadoop FS: Use the widest range of surfaces to manipulate any file system.Hadoop DFS and HDFs DFS: can only operate on HDFs file system-related (including operations with local FS), which is already deprecated, typically using the latter.The following reference is from StackOverflowFollowing is the three commands which appears same but has minute differences
Hadoop fs {args}
The debug run in Eclipse and "run on Hadoop" are only run on a single machine by default, because in order to let the program distributed running in the cluster also undergoes the process of uploading the class file, distributing it to each node, etc.A simple "run on Hadoop" just launches the local Hadoop class library to run your program,No job information is vi
Now that namenode and datanode1 are available, add the node datanode2 first step: Modify the Host Name of the node to be added hadoop @ datanode1 :~ $ Vimetchostnamedatanode2 Step 2: Modify the host file hadoop @ datanode1 :~ $ Vimetchosts192.168.8.4datanode2127.0.0.1localhost127.0
Now that namenode and datanode1 are available, add the node datanode2 first step: Modify the Host Name of the node to be added
(1) First create Java projectSelect File->new->java Project on the Eclipse menu.and is named UploadFile.(2) Add the necessary Hadoop jar packagesRight-click the JRE System Library and select Configure build path under Build path.Then select Add External Jars. Add the jar package and all the jar packages under Lib to your extracted Hadoop source directory.All jar packages in the Lib directory.(3) Join the Up
This article has agreed:Dn:datanodeTt:tasktrackerNn:namenodeSnn:secondry NameNodeJt:jobtrackerThis article describes the communication protocol between the Hadoop nodes and the client.Hadoop communication is based on RPC, a detailed introduction to RPC you can refer to "Hadoop RPC mechanism introduce Avro into the Hadoop RPC mechanism"Communication between nodes
This article will go on to the wordcount example in the previous article to abstract the simplest process and explore how the System Scheduling works in the mapreduce operation process.
Scenario 1: Separate data from operations
Wordcount is the hadoop helloworld program. It counts the number of times each word appears. The process is as follows:
Now I will describe this process in text.
1. The client submits a job and sends mapreduce programs and dat
Meet hadoop
1.1 data! (Data)
Most of the data is locked up in the largest Web properties (like search engines), or scientific or financial institutions, isn' t it? Does the advent of "big data," as it is beingCalled, affect smaller organizations or individuals?
As ordinary people do not benefit from the vast amount of data, data is stored in the network or stored by a large number of research institutions, so big data mining is also applied.
From a pe
1. Preface
Hadoop RPC is mainly implemented through the dynamic proxy and reflection (reflect) of Java,Source codeUnder org. Apache. hadoop. IPC, there are the following main classes:
Client: the client of the RPC service
RPC: implements a simple RPC model.
Server: abstract class of the server
Rpc. SERVER: specific server class
Versionedprotocol: All classes that use the RPC service mu
I perform the following steps:1. dynamically increase datanode nodes and Tasktracker nodesin host226 as an exampleExecute on host226:Specify host NameVi/etc/hostnameSpecify host name-to-IP-address mappingsVi/etc/hosts(the hosts are the Datanode and TRAC)Adding users and GroupsAddGroup HadoopAddUser--ingroup Hadoop HadoopChange temporary directory permissionschmod 777/tmpExecute on HOST2:VI conf/slavesIncrease host226Ssh-copy-id-i. ssh/id_rsa.pub [Emai
Hello everyone, I am Stefan, starting today to bring you a detailed Hadoop learning tutorial, you can follow my tutorial step by step into the development of cloud computing, OK, nonsense, we started the first: Hadoop environment.
The beginning of everything is difficult, this is not a blow. Many people in the initial environment to build up the problem, and everyone's platform and there are differences, it
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