How can I move data from one disk to another?

As per discussion at Why Cluster Status is Red, please help, I am thinking to move my data files to another faster volume. What is the standard procedure?

Second, if I change the node name, will it affect the indexes?

Depends how you have things setup now in relation to mounts and ES config.

You can change node name, it won't impact data stored. But changing cluster name will.

I am running ELK stack on two Windows boxes. One is for Elasticsearch and Kibana and the other one is for Logstash. I am dumping logs on a mounted NAS (Synology) volume. I didn't change anything in ES config file except the and node name.

Let me know, if you need any further information.

That's what I mean.

You'll need to change that to the new path and then copy the data over.

So, first should I stop the ES service, right?

Yeah, definitely.