You can always run them. But in some situations repair cannot be used, and in this case new nodes cannot be added. The news.txt file is your friend there.
As a general rule when upgrading a cluster I move one node to the new version and let it soak in for an hour or so. Just to catch any crazy. I then upgrade all the nodes and run through the upgrade table. You can stagger upgrade table to be every RF'th node in the cluster to reduce the impact. Cheers ----------------- Aaron Morton Freelance Cassandra Developer New Zealand @aaronmorton http://www.thelastpickle.com On 11/02/2013, at 8:05 PM, Michal Michalski <mich...@opera.com> wrote: > >> 2) Upgrade one node at a time, running the clustered in a mixed >> 1.1.2->1.1.9 configuration for a number of days. > > I'm about to upgrade my 1.1.0 cluster and > http://www.datastax.com/docs/1.1/install/upgrading#info says: > > "If you are upgrading to Cassandra 1.1.9 from a version earlier than 1.1.7, > all nodes must be upgraded before any streaming can take place. Until you > upgrade all nodes, you cannot add version 1.1.7 nodes or later to a 1.1.7 or > earlier cluster." > > Which one is correct then? Can I run mixed 1.1.2 (in my case 1.1.0) & 1.1.9 > cluster or not? > > M.
