On a 3 node test cluster we recently upgraded one node from 2.0.10 to 2.0.11. This is a cluster that had been happily running 2.0.10 for weeks and that has very little load and very capable hardware. The upgrade was just your typical package upgrade:
$ dpkg -s cassandra | egrep '^Ver|^Main' Maintainer: Eric Evans <eev...@apache.org> Version: 2.0.11 Immediately after started it ran a couple of ParNews and then started executing CMS runs. In 10 minutes the node had become unreachable and was marked as down by the two other nodes in the ring, which are still 2.0.10. We have jstack output and the server logs but nothing seems to be jumping out. Has anyone else run into this? What should we be looking for? Peter