I upgraded my dev (8 nodes) and integration (33 nodes) clusters in December from CM 5.4 [with CDH 5.4.8 running on CentOS 6.5] to CM 5.5.    The upgrade of the CM to version 5.5 allowed the OS to be upgraded from CentOS 6.5 to 6.7.    The environments have been running successfully for a few weeks now so the production cluster will undergo the same upgrades. ... View more