In the documentation of DataStax Enterprise (DSE) 2.0 there is a chapter about "Elastic Workload Re-provisioning" (http://www.datastax.com/docs/datastax_enterprise2.0/workload_reprovisioning) but it the DSE 3.1 documentation this part is missing.
Is the old documentation still valid?
Is there a simple guide what steps are necessary to change a "5 node real-time cluster" into a "3 node realtime, 2 node analytics cluster" when there is already data in all 5 nodes?
Meanwhile I got some answer in the support forum at DataStax (http://www.datastax.com/support-forums/topic/documentation-on-elastic-workload-re-provisioning-missing-for-dse-31). I will summarize it here:
It is still valid but not recommended - that was the reason to remove it from the documentation. A cleaner approach would be to have seperate (virtual) datacenters for real-time and analytical nodes. With only one datacenter, the analytical batch jobs may cause latency issues with real-time write/reads in the same cluster.