I have built and existing demo cluster. It was working perfectly well.

however because of some changes, I have to change the IP address of each of the data nodes.

I did a grep -R 'oldIP' /etc on each machine and edited the files which contained the old IP addresses and replaced them with new IP.

I rebooted each machine.

However despite doing that when I do

sudo -u hdfs hadoop dfsadmin -report

it shows me 2 dead data nodes and it lists the old IP addresses.

How can I remove old IP and then replace them with new IP addresses?