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Questions tagged [namenode]

The Hadoop NameNode is the centerpiece of an HDFS file system. It keeps the directory tree of all files in the file system, and tracks where across the cluster the file data is kept.

The NameNode is the centerpiece of an HDFS file system. It keeps the directory tree of all files in the file system, and tracks where across the cluster the file data is kept. It does not store the data of these files itself.

Client applications talk to the NameNode whenever they wish to locate a file, or when they want to add/copy/move/delete a file. The NameNode responds to the successful requests by returning a list of relevant DataNodes where the data lives.

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can two machines be used for hadoop cluster?

I want to use one machine as a namenode, another machine as a datanode. After configuration, I can find datanode by using "jps" command. But I cant find the datanode when using "hdfs dfsadmin -report" on any of these two machines. So what's wrong?…
Chris
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namenode goes in safemode every time i re-start machine

I have Hadoop 1.x on ubuntu Everything works fine: I'm able to upload input file in HDFS. But when I reboot my laptop, all HDFS blocks are corrupted and NameNode starts in SafeMode So I have to 1) Leave the SafeMode 2) Delete all corrupted blocks…
Ankit dhoot
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Restore/recover the fsimage files

we have a cluster ( *ambari cluster with 3 master machines , 3 workers machines ) name-node is set on master01 and master03 Linux redhat machines version 7.3 we notice that after cluster restart ( machine reboot ) , we cant start the name-node…
enodmilvado
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Automatically connect to HDFS secondary NN from Java application, once the primary NN goes down

I have a simple java client that saves files to HDFS - configured with 1 name node. For this, I use a hadoop configuration, specifing the default filesystem like: org.apache.hadoop.conf.Configuration conf = new…
Asleep
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Hadoop - DataNode and Namenode not starting

I installed Hadoop on Ubuntu but when I run ./start-all.sh script in sbin folder the DataNode and Namenode not starting. I got the following settings in the config files: core-site.xml …
Yordanka Stoyanova
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Difference between Namespace and Metadata in Hadoop?

I'm learning hadoop and while studying am getting confused with two terms one Namespace and second is Metadata. What I have studied so far about metadata is Metadata is a part of namenode server. Its about all the information of files in HDFS,…
Nele
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FATAL ha.BootstrapStandby: Unable to fetch namespace information from active NN

unable start standby namenode. I have verified my configurations from official documentation.
vamsi
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Not able to access /tmp folder in HDFS

I have started the name node, datanode and mr service on my local machine and all the service are running. Here is what's the result of jps command: kv:~ karan.verma$ jps 4499 SecondaryNameNode 420 4676 NodeManager 4741 JobHistoryServer 5125…
KayV
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Why Hadoop name node connecting to weird [aca8ca1d.ipt.aol.com] hostname?

I am using a mac system and starting a hadoop system, using the command: start-dfs.sh and my hostname is "ctpllt072.local" as returned by "hostname" command. But i am getting a weird hostname and message when connecting starting the name node as…
KayV
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HBase High Availability without Namenode High Availability

I've set up a two node cluster using Ambari with HBase installed. I know that we can't achieve Namenode HA without three nodes. But can we make HBase high available with two nodes, by just adding a Standby HBase Master. Does Hbase high availability…
thanuja
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NameNode keeps going down

I am having a problem with the NameNode status ambari shows. The following is happening: - The NameNode keeps going down a few seconds after I start it through ambari (it looks like it never really goes up, but the start process runs…
ssobreiro
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Spark/YARN - not all nodes are used in spark-submit

I have a Spark/YARN cluster with 3 slaves setup on AWS. I spark-submit a job like this: ~/spark-2.1.1-bin-hadoop2.7/bin/spark-submit --master yarn --deploy-mode cluster my.py And the final result is a file containing all the hostnames from all the…
user1187968
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Not able to acess Namenode web URL

I tried accessing the web url of namenode with the namenode IP. It throwed an error HTTP ERROR 404 Problem accessing /dfshealth.jsp. Reason: NOT_FOUND I am able to access the Namenode web url with the hostname. /etc/hosts file: 127.0.0.1 …
Jon Andrews
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Browse the file system on namenode is not working: Hadoop installation

I have installed hadoop-1.2.1.I was able to configure name node and job trakcer , both are up and running. However when i am trying to click on the link "Browse the file system". i am automatically being redirected to…
Anvesha Saxena
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When YARN is running the hadoop job submitted get stuck in Accepted state

I am using VirualBox to run Ubuntu 14 VM on Windows laptop. I have configured Apache distribution HDFS and YARN for Single Node. When I run dfs and YARN then all required demons are running. When I don't configure YARN and run DFS only then I can…
Shailesh
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