How does Riak nodes distribute data

We have a single production node of riak for our game. We would like to backup our database constantly, so we decided to start up some other nodes.

We're trying to use AWS free tier. What we see is that some parts of data just moved to second node, leaving us with high pings to aws, sometimes timeouts.

Is that correct scheme of riak nodes working? Do they just distribute parts of data amongs them and DO NOT contain whole database in case of disaster?

We are using LevelDB backend. Thank you.