the followings are the common procedures when doing a cluster/OS upgrade.
1. read the release notes of the new VCS version you planned to upgrade to
2. review the VCS installation guide and VCS agent release notes to know the new OS kernel/application compatibility and other system requirement
3. do a full back up (including collect new VRTSexplotre/DataCollector) from each node
4, schedule a sufficient long maintenance window
.5. Once the new OS upgrade is complete, run VCS installer with "-precheck to find out if the systems are ready for new VCS installation.
6. after completing VCS upgrade, perform a SG failover test
Good luck
6.