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Multiple datanodes on the same machine?

Multiple datanodes on the same machine?

Expert Contributor

Hi,

 

Is it possible to have multiple datanodes on the same machine in Cloudera using CM? Obviously this can be done in plain Apache Hadoop. 

4 REPLIES 4

Re: Multiple datanodes on the same machine?

Champion

@RajeshBodolla

 

Not sure I get your intension to have multiple datanodes on the same machine

 

if you want to store data nodes in different/multiple directories in the same machine then you can use CM -> HDFS -> Configuration -> datanode.data.dir and specify your directories

Re: Multiple datanodes on the same machine?

Expert Contributor

Hi,

 

I can add/remove the data directories. Want i want to add 2 new datanode instances on a single host from CM.

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Re: Multiple datanodes on the same machine?

Community Manager

Hadoop wasn't designed to run multiple DataNodes on a single host and is prohibited by Cloudera Manager.   

 

The reason for a single DataNode per host is to prevent data loss.  Using the default replication factor of 3, every block in a file will be replicated to 3 different hosts.   If a host containing a block replica were to go down, the NameNode will mark the block as under-replicated.  A new copy of the block will be created on another DataNode bringing the number of replicas back to 3.  

 

If you do not care about data integrity my suggestion is to set the replication factor to 1 or use virtual hosts. 



David Wilder, Community Manager


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Re: Multiple datanodes on the same machine?

Expert Contributor
@denole

Yes, i agree with your point. my notion of this was to test when we have quickstart VM for testing.
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