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
Once Hadoop is installed, you will often be prompted with a warning:
WARN util. nativecodeloader:unable to load Native-hadoop library for your platform ...
Using Builtin-java classes where applicableSearched a lot of articles, all say is related to the system bit number, I use CentOS 6.5 64-bit operating system.
The first two days in the Docker image to find a step to solve the problem, the pro tried
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
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
(Big podium: the first in-country it online education hybrid adaptive Learning)1.3 Modes A Hadoop cluster can run
Stand-alone (local) mode
Pseudo-distributed mode
Fully distributed mode
2. note points in stand-alone (local) mode?There is no daemon in stand-alone mode (standalone), and everything runs on a JVM. There is also no DFS here, using the local file system. Stand-alone mode is suitable for running mapreduce programs durin
(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
ArticleDirectory
Insecure
Secure Mode
No downtime is required for adding or deleting machines in the hadoop cluster, and the entire service is not interrupted.
Before this operation, the hadoop cluster is as follows:
HDFS machines are as follows:
The MR machine is as follows:
Add Machine
On the master machine of the cluster, modify the $ hadoop_home/CONF/slaves file and add t
The recently read material always mentions Hadoop 0.20, 0.23, and so on, causing individuals to be quite surprised by the version of Hadoop: 1.2.1 is still behind the 0.23, you are kidding me. Curiosity, a search, found a document, the following are from the document, here to make a backup.Excerpted from Dylan. Advanced applications for Hadoop Big Data Solutions-
The compilation process is very long, the mistakes are endless, need patience and patience!! 1. Preparation of the environment and software
Operating system: Centos6.4 64-bit
JDK:JDK-7U80-LINUX-X64.RPM, do not use 1.8
Maven:apache-maven-3.3.3-bin.tar.gz
protobuf:protobuf-2.5.0.tar.gz Note: Google's products, preferably in advance Baidu prepared this document
Hadoop src:hadoop-2.5
Hadoop exception and handling Summary-01 (pony-original), hadoop-01
Test environment:
Local: MyEclipse
Cluster: Vmware 11 + 6 Centos 6.5
Hadoop version: 2.4.0 (configured as automatic HA)
Test Background:
After four normal tests of the MapReduce Program (hereinafter referred to as MapReduce), a new MR program is executed, and the console information of MyEclipse
Hadoop learning 2: hadoop LearningAfter building a pseudo-distributed system:Introduction to pseudo distributed installation: http://www.powerxing.com/install-hadoop/
Exercise 1 compile a Java program to implement the followingFunction:
1. In HDFSUpload files
2. From HDFSDownload filesTo local
3.Show file directory
4.Move files
5.Create folder
6.Remove folder
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