Some notes on hadoop cluster

One way Passwordless SSH from Master to worker nodes:

1. Generate Key: ssh-keygen -t rsa
2. Create folder in worker node: ssh [user]@ mkdir -p .ssh
3. Copy key to worker node: ssh-copy-id [user]@
4. Enable permissions to worker: ssh [user]@ "chmod 700 .ssh; chmod 640 .ssh/authorized_keys"

700 — user can read, write and execute. group and others have no permissions
640 — user can read and write. group can read. others have no permissions

Configuration Files: (For minimal configuration)

core-site.xml configuration should be the same for master and all worker nodes. Namenode URL ( should point to master node only.
mapred-site.xml should be edited only on master node.
yarn-site.xml should be the same configuration on master and worker nodes.
the file “slaves” should be updated only in the master node.
hdfs-site.xml is self explanatory

Disable IPV6:

IPV4 – Internet Protocol Version 4 — IP address follows this pattern:

IPV6 – Internet Protocol Version 6 — IP address follows this pattern:

Hadoop works/communicates on IPV4 within its cluster. It does not support IPV6 at the moment.

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