Migrating OSS cassandra cluster from OnPrem to Cloud with 'Add datacenter' approach and trying to reconcile the difference between two documents I am following to replicate system keyspaces-
The blog http://www.redshots.com/moving-cassandra-clusters-without-downtime-part-1/ suggests replicating system keyspaces first as we are adding nodes, while the Datastax documentation https://docs.datastax.com/en/dse/6.8/dse-admin/datastax_enterprise/operations/opsAddDCToCluster.html suggests doing all at the same time, in step 9
1. Is there any reason to replicate the system keyspaces to new DC first with alter keyspace command as suggested in the redshots blog or it doesn't matter that much?
2. If replicating system keyspaces first is recommended, as suggested in redshots blog, are we just replicating new data in those keyspaces, since I didn't see them suggesting to run nodetool rebuild until later which will replicate existing data.
Appreciate your guidance to clarify this.