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HDFS >> mail # user >> Re: Issue: Namenode is in safe mode


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Shumin Guo 2013-03-06, 16:30
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Re: Issue: Namenode is in safe mode
you can not directly remove a datanode from a cluster its not a proper way.
you need to decommission nodes and wait till the data from the datanode to
be removed are copied to other nodes.
just read document for proper decomissioning of nodes

http://helpmetocode.blogspot.in/2012/11/datanode-decommissioning-from-hadoop.html


Shashwat Shriparv

On Wed, Mar 6, 2013 at 10:00 PM, Shumin Guo <[EMAIL PROTECTED]> wrote:

> To decommission a live datanode from the cluster, you can do the following
> steps:
>
> 1, edit configuration file $HADOOP_HOME/conf/hdfs-site.xml, and add the
> following property:
> <property>
> <name>dfs.hosts.exclude</name>
> <value>$HADOOP_HOME/conf/dfs-exclude.txt</value>
> </property>
>
> 2, put the host name of the node you want to decommission onto file
> $HADOOP_HOME/conf/dfs-exclude.xml (one host per line).
>
> 3, Run the following command:
> hadoop dfsadmin -refreshNodes
>
> Shumin
>
> On Wed, Mar 6, 2013 at 5:29 AM, AMARNATH, Balachandar <
> [EMAIL PROTECTED]> wrote:
>
>> The repliation factor was 1 when I removed the entry of A in slaves file.
>> I did not mark it retirement. I do not know yet how to mark a node for
>> retirement. I waited for few minutes and then I could see thte namenode
>> running again****
>>
>> ** **
>>
>> *From:* Nitin Pawar [mailto:[EMAIL PROTECTED]]
>> *Sent:* 06 March 2013 15:31
>> *To:* [EMAIL PROTECTED]
>> *Subject:* Re: Issue: Namenode is in safe mode****
>>
>> ** **
>>
>> what is your replication factor?****
>>
>> when you removed node A as datanode .. did you first mark it for
>> retirement? if you just removed it from service then the blocks from that
>> datanode are missing and namenode when starts up it checks for the blocks.
>> Unless it reaches its threshold value it will not let you write any more
>> data on your hdfs. ****
>>
>> ** **
>>
>> I will suggest to start datanode on A, then mark it for retirement so
>> namenode will move the blocks to new datanode and once it is done namenode
>> will retire that datanode. ****
>>
>> ** **
>>
>> ** **
>>
>> ** **
>>
>> On Wed, Mar 6, 2013 at 3:21 PM, AMARNATH, Balachandar <
>> [EMAIL PROTECTED]> wrote:****
>>
>>  ****
>>
>> Hi, ****
>>
>>  ****
>>
>> I have created a hadoop cluster with two nodes (A and B). ‘A’ act both as
>> namenode and datanode, and ‘B’ act as datanode only. With this setup, I
>> could store, read files. Now, I added one more datanode ‘C’ and relieved
>> ‘A’ from datanode duty. This means, ‘A’ act only as namenode, and both B
>> and C act as datanodes. Now, I tried to create a directory, it says****
>>
>>  ****
>>
>> ‘ org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot create
>> directory Name node is in safe mode’****
>>
>>  ****
>>
>>  ****
>>
>> Can someone tell me why the namenode now is in safe mode?****
>>
>>  ****
>>
>> With thanks and regards****
>>
>> Balachandar****
>>
>>  ****
>>
>>  ****
>>
>>  ****
>>
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>>
>>
>> ****
>>
>> ** **
>>
>> --
>> Nitin Pawar****
>>
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NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB