My expectation is that in trunk SCM CASSANDRA_4 would change to SCM CASSANDRA_5. I think we should be striving to support full downgrade/rollback ability to the previous major version from trunk. With TCM I would expect that when running in CASSANDRA_5 mode that initializing TCM would not be possible, as once initialized you could no longer roll back. Do we have no way to support the gossip paths continuing to work prior to initializing TCM?
-Jeremiah On Dec 11, 2024 at 7:41:48 AM, Sam Tunnicliffe <s...@beobal.com> wrote: > My point is that the upgrade to 5.1/6.0 isn't really complete until the > CMS is initialised and this can't be done while running with SCM > CASSANDRA_4 because of the messaging service limitation. Until that point, > schema changes & node replacements are not supported which affects how long > a bake time is tolerable. > This specific issue could probably be fixed by revisiting the SCM > implementation in 5.1/6.0, so we should certainly do that but the fact > remains that we don't have great test coverage to indicate how clusters > behave when running in SCM for a prolonged period. > > Thanks, > Sam > > On 11 Dec 2024, at 13:29, Brandon Williams <dri...@gmail.com> wrote: > > > On Wed, Dec 11, 2024 at 7:22 AM Sam Tunnicliffe <s...@beobal.com> wrote: > > > > > > so running in any SCM mode for a prolonged period is not really viable. > > > This is what many users want to do though, upgrade one DC and let it > > bake to see how it goes before continuing. I don't think that's > > unreasonable, but from working on CASSANDRA-20118 I know how difficult > > that is already. I don't think we've built enough SCM muscle yet to > > think about handling multiple previous versions. > > > Kind Regards, > > Brandon > > >
