I'm not sure I 100% understand the question, but the things covered in CEP-21 won't enable you to as an operator to bootstrap all your new nodes without fully joining, then perform an atomic CAS to replace the existing members. CEP-21 alone also won't solve all cross-version streaming issues, which is one reason performing topology-modifying operations like bootstrap & decommission during an upgrade are not generally considered a good idea.
Transactional metadata will make the bootstrapping (and decommissioning) experience a whole lot more stable and predictable, so in the short term I would expect the recommended rolling approach to upgrades would improve significantly. > On 20 Oct 2022, at 12:24, Claude Warren, Jr via dev > <dev@cassandra.apache.org> wrote: > > After CEP-21 would it be possible to take a cluster of 6 nodes, spin up 6 new > nodes to duplicate the 6 existing nodes and then spin down the original 6 > nodes. Basically, I am thinking of the case where a cluster is running > version x.y.z and want to run x.y.z+1, can they spin up an equal number of > x.y.z+1 systems and replace the old ones without shutting down the cluster? > > We currently try something like this where we spin up 1 system and then drop > 1 system until all the old nodes are replaced. This process frequently runs > into streaming failures while bootstrapping. > > Any insights would be appreciated. > > Claude
