We avoid mixing versions for a long time, but we always upgrade one node and check the application is happy before proceeding. e.g. wait for 30 minutes before upgrading the others.
If you snapshot before upgrading, and have to roll back after 30 minutes you can roll back to the snapshot and use repair to fix the data on disk. Hope that helps. ----------------- Aaron Morton New Zealand @aaronmorton Co-Founder & Principal Consultant Apache Cassandra Consulting http://www.thelastpickle.com On 9/01/2014, at 7:24 am, Robert Coli <rc...@eventbrite.com> wrote: > On Wed, Jan 8, 2014 at 1:17 AM, Jiri Horky <ho...@avast.com> wrote: > I am specifically interested whether is possible to upgrade just one > node and keep it running like that for some time, i.e. if the gossip > protocol is compatible in both directions. We are a bit afraid to > upgrade all nodes to 1.2.13 at once in a case we would need to rollback. > > This not not officially supported. It will probably work for these particular > versions, but it is not recommended. > > The most serious potential issue is an inability to replace the new node if > it fails. There's also the problem of not being able to repair until you're > back on the same versions. And other, similar, undocumented edge cases... > > =Rob >
