Multiple folders inside nodes folder

[aviral_srivastava]

Red Hat Enterprise Linux Server release 7.2 (Maipo)
elasticsearch 2.1.1

Inside the path
/home/appadmin/elasticsearch-2.1.1/data/linux-elasticsearch/nodes
there are two folders namely "0" and "1"

Why there are two folders ??
By nodes, I understand the physical server, how is that folder "1" is created
Secondly, elasticsearch is showing indices from "1" folder and not "0" folder. Why is that so ??
If I need, elasticsearch to use "0" folder , can I just delete "1" folder. Will that help ??

My elasticsearch was showing all the indices from "0" folder earlier, although I was having shards failed exception for some indices, So I restarted elasticsearch and now it is referencing indices from "1" folder

[jasontedor]

This means that you had two nodes running at the same time at some point, the nodes/1/ directory is from the second node. This was due to a bad default value for node.max_local_storage_nodes to permit multiple nodes to share the same data directory. This is fixed in 5.0.0, the default is now 1.