Multiple datanodes on the same machine?

[#1]

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. 

[#2]

@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

[#3]

Hi,

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

[#4]

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. 

[#5]

@denole

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