What to do with replication factor when reducing a Cassandra cluster?

Question

I have a 3 nodes Cassandra cluster with 2 keyspaces. One of them has replication factor 1 and the other, replication factor 2. I want to reduce the cluster, using nodetool decommission, to remove 2 nodes and leave only one (single node cluster).

So, what must I do with the replication factor? I think both keyspaces must have replication factor 1, but when must I modify it? Before decommission?

Thanks a lot!

Answer 1

您需要将复制因子减小为1，并且应该在停用2个节点之前执行此操作。

Answer 2

You must reduce the RF to 1 before the decommissioning and you must also run a repair on the keyspace you are reducing the RF on to be on the safe side. Then you can proceed with the decommissioning in a sequential manner.