shard splitting and indexes on hadoop

[Roberto Maggi @ Debian]

Hi you all,
I'm still new to solr and hadoop and I can't find an answer  to this 
question that rose in me.

In a multi cluster setup with 3 solr9 hosts and and 3 hadoop datanodes 
I'm wondering where and how the data is stored.

If I instruct the creation of a collection with 3 shard splitting, 1/3 
on each solr node, but the indexes are actually wrote onto the hadoop 
node: how would it work?

Thanks in advance.