Cassandra nodes are not equal
We had a solution but don't know how it happened. Here what we did:


Took snapshot of both servers in case of data loss over AWS
We detached Volume where data is stored. (for instance 172.x.y.k)
We formatted instance and loaded Cassandra with new version. Then we
attached Volume where data is stored.
Finally we started nodetool repair --full in terminal and it took 4
days.


Now our nodes are equal.