title: Data Partitioning and Replication on Cassandra cluster
body: <p>I have a 3 node Cassandra cluster with RF=3. Now when I do <code>nodetool status</code> I get the <strong>owns</strong> for each node in the cluster as 100%.</p>
  
  <p>But when I have 5 nodes in the cluster wit RF=3. The <strong>owns</strong> is 60%(approx as shown in image below).</p>
  
  <p>Now as per my understanding the partitioner will calculate the hash corresponding to first replica node and the data will also be replicated as per the RF on the other nodes. 
  Now we have a 5 node cluster and RF is 3. </p>
  
  <p>Shouldn't 3 nodes be owning all the data evenly(100%) as partitioner will point to one node as per the partitoning strategy and then same data be replicated to remaining nodes which equals RF-1? It's like the data is getting evenly distributed among all the nodes(5) even though RF is 3.</p>
  
  <p><a href="https://i.stack.imgur.com/BU4K5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BU4K5.png" alt="enter image description here"></a></p>
  
  <p><strong>Edit1</strong>:</p>
  
  <p>As per my understanding the reason for 60%(approx) <strong>owns</strong> for each node is because the RF is 3. It means there will be 3 replicas for each row. It means there will be 300% data. Now there are 5 nodes in the cluster and partitioner will be using the default random hashing algorithm which will distribute the data evenly across all the nodes in the cluster.</p>
  
  <p><strong>But now the issue is that we checked all the nodes of our cluster and all the nodes contain all the data even though the RF is 3.</strong> </p>
  
  <p><strong>Edit2</strong>:</p>
  
  <p>@Aaron I did as specified in the comment. I created a new cluster with 3 nodes.</p>
  
  <p><a href="https://i.stack.imgur.com/GwMbq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GwMbq.png" alt="enter image description here"></a> </p>
  
  <p>I created a Keyspace "test" and set the class to simplestrategy and RF to 2.</p>
  
  <p><a href="https://i.stack.imgur.com/ytYBl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ytYBl.png" alt="enter image description here"></a></p>
  
  <p>Then I created a table "emp" having partition key (id,name).</p>
  
  <p><a href="https://i.stack.imgur.com/yt6cv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yt6cv.png" alt="enter image description here"></a></p>
  
  <p>Now I inserted a single row into the first node.</p>
  
  <p>As per your explanation, It should only be in 2 nodes as RF=2.</p>
  
  <p>But when I logged into all the 3 nodes, i could see the row replicated in all the nodes.</p>
  
  <p>I think since the keyspace is getting replicated in all the nodes therefore, the data is also getting replicated.</p>